Downgrade to 5.0 - Network/SQL Problems

I am having problems with accessing a SQL Database server in Parallels 6.0 using Windows XP. Sometimes it works fine, sometimes it is painfully slow. It is difficult to determine what is causing this problem. Tried turning off Kaspersky. No luck. When it does occur, it seems that I need to reboot VM and OSX. Other programs that are not accessing a SQL server on network are fine.

Can I just downgrade for the time being? If so, how do I do it?