After changing the memory setting for a Windows XP SP2 Professional VM from 512MB to 1 GB, I get the following error: "Unable to allocate virtual machine memory! This error may occur mostly if there is not enough free disk space . . . " The VM disk and the host disk both have enough free space. I have tried all of the disk maintenance and compression tools, reinstalled Parallels, restarted Mac, etc. (Sent these comments to beta at Parallels too)
I also get this error VERY frequently and was quite irritated to find that RC2 did not fix it. Are you on a Mac Pro by chance?
I have also seen this... I've never had it cause a problem it just flashes the error warning box and continues on as if nothing happened. Core1 duo Macbook, 3150.