Parallels tools keeps installing

After a fair bit of trouble getting v4 running yesterday, I managed with the help of the guys at Parallels to get it all going.

Finally got the tools installed after if stalling at "Installing Shared folders" (ticket #617122) and thought that was the end of it.

This morning however, I keep having to reinstall the tools every time I run the vm, although it doesn't actually seem to install anything (judging by the speed it does this at), just asks to reboot the vm. Submitted a report id#12402.