Cannot resize HDD of VM created in P5 using P6

Pretty much what the title says, Parallels 6 won't let me expand the HDD of my WinXP vm which i created a while ago using Parallels 5. It seems that the lock is closed, is there any way to open it? Creating another VM from zero would be very inconvenient in my situation.

Thanks.

 

I'm experiencing exactly the same problem.

In addition, trying to compress the same image, after some minutes, fails saying bacause of the presence of snapshots (none is actually present) or disk corruption (I checked with chkdsk and it is ok).

Also, it seems the image now increases over and over.

Any solution to this problem?