Run regedit from 'START' 'RUN' 'regedit', press OK
Look in
HKLM/SYSTEM/CURRENTCONTROLSET/CONTROL/SESSION MANAGER/MEMORY MANAGEMENT
<DiasblePagingExecutive> should be '0'
<Paging files> should be something like 'C:\pagefile.sys 256 512'
If <Paging Files> is something else, just delete content and exit.
Set the size of the virtual memory as usual in
My Computer/Properties/Advanced/Performance/Virtual Memory
Restart
Hopefully this solved your problem, it solved my problem that was similar.