They can be caused by one or more of the following:
- Kinked or damaged cable - just because it looks ok doesn't mean it is - test it or swap it out for another one you may have.
- Cable running close to a fluorescent light ballast (fixture)
- Loose connector/plug on cable
- Old "worn out" cables, particularly coax cables that have been around for years
- Out of date drivers
- Bad hub or a bad port on a hub
- Failed/failing network card
- Power problems (PLEASE protect your systems with a UPS, power problems are one of the biggest troublemakers we know of. Yes, a UPS might cost $79 to $450 depending on how big a unit you buy, but how much is your computer and a day's worth of business worth? Consider it much less than the time to fix a power-caused mess.
- Network setup and/or configuration problems.
- Inadvertent shutdowns
- Shutting down servers while workstations are still in the program
- Out of date network drivers (even those right out of the box are sometimes a problem)
- Improper or less than desirable network bindings/settings
NOTE: Remember that having backups is a saving grace in the face of file/network problems. Network problems can corrupt your files in a heartbeat. If you have no backups, you are in big trouble (future or present - trouble will occur). Having backups is a responsibility you must take VERY seriously.
Drivers up to date? Windows networking is subject to a number of problems, MANY of which can be solved simply by installing updated driver software from the manufacturer or (more often) Microsoft. The link below will go to a web page that describes just ONE of the problems in Windows peer-to-peer networking, yet there are several other problems referenced at the bottom of that page. In particular, anyone on Windows 95 needs to get their network drivers and "requestor" updated.
http://support.microsoft.com/support/kb/articles/q174/3/71.asp and
http://support.microsoft.com/support/kb/articles/q148/3/67.asp in particular note some problems that can burn you.
Windows NT users - Are you on service pack 6 instead of service pack 6a or another service pack? If so, expect lots of problems. Microsoft has acknowledged that service pack 6 broke a lot of things network-wise. You can get service pack 6a at their site or you can go back to service pack 5, either of which is stable. In addition, do NOT mix service packs on different NT machines on your network. In other words, run all your NT machines on service pack 5 or on service pack 6a, but not a mix of both service packs.
Power management - Do you have Energy Star features on your computers?
Probably so. Power management and networking DO NOT MIX. You can have your
computers' power management features turn off and/or dim the monitor, but DO NOT
have them turn off the hard drive, network cards etc. This will definitely cause
you grief when computers are networked. Grief = lost data
Database corruptions, timeouts and other troubles. Another issue is the
various ways that Windows9x and NT try to improve performance, often at the
price of stability. Sometimes these things work, other times they cause network
timeouts because they force additional file operations behind the scenes and
those file operations time out (fail). One way to turn one of these items off is
to turn off "Synchronous buffer commits". To do this, click Control Panel,
System, Performance, File System, Troubleshooting and check the "Disable
synchronous buffer commits" checkbox.
Database corruptions, timeouts and other troubles, Part II. Further, Windows
NT users face issues caused by some performance improvements that NT tries to
implement with network applications by 'faking' multiple use of files.
Unfortunately, some users experience file corruption because of this. This
article is a bit of nerd-speak, but your network person should take a look at it
if you are seeing "Access denied" errors on network files when they *know* that
the network permissions are set properly.
http://support.microsoft.com/support/kb/articles/Q129/2/02.asp The topic of this
article can also be the cause of database corruption and network timeouts (drive
not available messages and the like).
Win9x/Me users - Turn off write caching You need to disable the "write-behind
cache". When the program ask to save the data, the data is kept in cache on the
local machine [until the cache is flushed] instead of being on the
server.
START > SETTINGS > CONTROL PANEL
System
Performance
tab
Troubleshooting
Performance
Disable the write-behind
cache
Restart the computer
Windows 2000 users - Turn off write caching You need to disable the
"write-behind cache". When the program ask to save the data, the data is kept in
cache on the local machine [until the cache is flushed] instead of being on the
server.
Right Click MY Computer > Properties > Hardware > Device
Manager
Right Click Disk Drive > Properties
Disable: Write Cache
Enabled
Restart the computer
Opportunistic locking is a Windows-specific mechanism for client/server
databases to allow multiple processes to lock the same file while allowing for
local (client) data caching to improve performance over Windows networks.
Microsoft's documentation states "An opportunistic lock (also called an
oplock) is a lock placed by a client on a file residing on a server. In most
cases, a client requests an opportunistic lock so it can cache data locally,
thus reducing network traffic and improving apparent response time.
Opportunistic locks are used by network redirectors on clients with remote
servers, as well as by client applications on local servers" and "Opportunistic
locks are requests from the client to the server. From the point of view of the
client, they are opportunistic. In other words, the server grants such locks
whenever other factors make the locks possible.".
You can read more about opportunistic locking in Microsoft's documentation
http://support.microsoft.com/default.aspx?scid=kb;en-us;q124916
Some Client Applications Fail when writing to Windows NT
http://support.microsoft.com/default.aspx?scid=kb;en-us;q129202
PC EXT: Explanation of Opportunistic locking in Windows NT
http://support.microsoft.com/default.aspx?scid=kb;en-us;q138365
How the auto disconnect works in Windows NT
http://support.microsoft.com/default.aspx?scid=kb;en-us;q142803
Locking error or Computer hangs Accessing network database files
http://support.microsoft.com/default.aspx?scid=kb;en-us;q148367
Possible network file damage with redirector caching
http://support.microsoft.com/default.aspx?scid=kb;en-us;q152186
Possible network data corruption if locking not used
http://support.microsoft.com/default.aspx?scid=kb;en-us;q163401
How to disable network redirector file caching
http://support.microsoft.com/default.aspx?scid=kb;en-us;q174371
Possible database file damage when data is appended
http://support.microsoft.com/default.aspx?scid=kb;en-us;q219022
Improving performance of MS-DOS database applications
http://support.microsoft.com/default.aspx?scid=kb;en-us;q296264
Configuring opportunistic locking in Windows 2000
http://support.microsoft.com/default.aspx?scid=kb;en-us;q290757
Write caching settings for hard disk may not persist after you restart your computer
Another NT issue re: slow network performance with Service
Pack 4, 5, 6, or 6a (Q249799)
http://support.microsoft.com/default.aspx?scid=kb;en-us;q249799
