win 7 keeping in RAM il2?

I’ve some problem sometime with server mod or not but both with control of CRT

for example:
I play with UP2.0
now switch at 4.09
after I’ll join in 4.09 server and I’ll kick from server for CRT

I don’t use JSME for switch version but I’ve 3 installation

Yesterday for unknown reson I Joined 4.09 server and it works

Question is : Can operative sistem like Win 7 and Vista keep in memory files of other version of il2 or the check is done on the ours HD?