You must be using XP. The message was well known to us old gits.
Virtual memory, or paging file is a section of the hard disc used by the system as RAM when it runs a bit short. Unfortunately it gives warnings about its alleged lack of capacity without good cause.
System properties (in blue, top line),
Advanced system settings (in blue on left),
Performance, - settings,
Remove max and min settings and set to "system managed size" , click apply and everything else it wants you to do, then do a restart to make it stick.
You will stop getting the silly warnings, and your computer will work OK.
In theory installing more RAM should solve this problem, but I found that it did not, although it speeded up start-up a lot.
(I did the commands for Vista, to find Virtual memory, but it should be similar for other Windows systems).
Same problem with XP years ago.