low on virtual memory

hello Sir's / Maam.. heres the error ^^

The instruction at 0x10008dd0 referenced memory at 0x00590650. The memory could not be written. Click OK to terminate program.

i am playing Mu.. which doesnt require that much memory.. hadnt been like that for almost a year.. already did clean ups on temporary files.. internet files.. did hard disk space.. so this just occurred just yesterday.. uh.. im running 512 mb ddr ram and on 32bit processor.. and on Windows xp sp2.. well tried making the virtual memory max and still keeps popping up.. and wont let me play MU.. and so.. i did format.. and reinstalled xp.. and still same thing happened.. virtual memory still low... thnx guys.. would be a great help if u can help me out..