X:\ is not accessible. Insufficient system resources exist to complete the requested service. Help
Solution 1:
Here's a little tip for the first time poster: More detail is good. It makes it easier for us to respond to your specific question. What is going on largely depends on what software you are running. I did some digging and the error you are getting is normally an issue that is related to very large (multi-GB) files around. If that's what you are doing, then you might need to look at non-microsoft NAS solutions for data storage. Everything I have read states that this is a known issue without an easy workaround.
Before you go running out to get a bunch of expensive hardware, you should first answer a few questions:
What is hosting the network drive? If it's a Windows XP home or Pro machine, then you'll need to move the share to a Windows server installation.
How many computers can you connect before this issue happens? Is it a consistent number? If the number changes, then it could be a software/hardware issue. If it is the same every time, then there is a configuration limit somewhere. You might have to rethink your storage setup.
You mention that if you close a program, then the system works. What program are you closing and on what machine? that app may not be optimized to work over a network connection and will require that you do local caching of files.
If you can update your question with more detains, we might be able to come up with a solution.
[EDIT]
http://social.microsoft.com/Forums/en-US/whssoftware/thread/f69097e4-0784-444f-9676-95f0e19ac03a/
http://support.microsoft.com/kb/304101
http://www.howtofixcomputers.com/forums/windows-xp/insufficient-system-resources-exist-complete-requested-serv-254559.html
[EDIT]
Solution 2:
Sounds like you have a problem with your memory pools (paged and non-paged). Since it's showing on multiple, different computers, then it's probably being caused by a common piece of software with a memory leak.
You can get the pool size numbers from Task Manager under the Performance tab, in the "Kernel Memory" box.
These should generally be under 100MB each, and anything over ~150MB start causing big-time problems (this is more so in the case of the Non-paged pool). Check them once when it reboots, record the numbers, then check the machine again when the problem has shown up and see if they've gotten way higher.
If so, you can use Poolmon from MS to monitor and diagnose those pools. By using the pool tagging system you can identify what's eating up your pools.
Often it's malfunctioning anti-virus, but could be just about anything. Luckily, since the computers are different, it's probably not a hardware driver issue.
HTH