Are you certain that it specifically said virtual memory? This doesn't seem to make any sense at all.
If it said 3Mb Free memory or Free Disk space, that would make a little sense, if the games are old ones. Many older programs used to include a routine to check for adequate disk space and/or memory, but are simply not capable of dealing with the large sizes we use today - hence they assume that there is not enough availabe, when the real problem is that there is more available than the programmers ever foresaw.