Virtual Memory is just a page file or a swap file on your hard drive that is essentially treated as if it were RAM.
If I'm not mistaken, the VM setup is a little different between Windows versions. The earlier releases use a specified drive for VM. In that case, you basically run out of VM when you run out of space on the specified drive. In newer releases of Windows, you specify the drive used for VM along with the size constraints to be used for the page file. In that case, you run out of VM when your page file hits its maximum allowed size.
If you're getting a message stating that VM is low, check to see how much space is on your local drive. If you're almost out when you get the message, you need to free up space. If you have plenty of space when you get the message, check the size of the page file with its size restrictions and proceed accordingly. If both look ok, bring it to the attention of your IT guys. It's best to let them deal with it.
Of course, always check with your IT guys before doing such things. We, the IT department I'm in, don't like our users doing these types of things without first talking with us, and your IT guys probably feel the same way.
Good luck. --
Jonathan