.PVM Files keep increasing in size

Dear All,

I have an iMAC 10.6.1 running Parallels Desktop for MAC version 4 with the latest build 3848.
I have 2 Virtual Machines and guest O/S's of Vista Business and Windows 7. The Vista Business has been running for quite a while and the Windows 7 was added recently.

I've noticed recently that the .pvm files are steadily increasing in size. even though I'm not adding any S/W (Both Virtual Machines)This was noticed after opening and shutting down the guest O/S. For example today after running Windows 7 for 45 minutes and NOT doing any work just leaving it idle. The .PVM grew by 45.29mb.

I have been observing this problem now for the past few weeks and have addressed this issue with support, sadly though we are not making progress.

To help narrow the problem down I have disabled windows updates not that Windows 7 has had many yet. and removed my external disk drive. The increase still occurs. I have ran the compressor only yesterday (Friday) and though it reduced my Windows 7 pvm from 26.4GB to 15.17GB it has started to increase steadily again.

Please note though I don't regularly use the Vista Virtual Machine The problem exist in both Virtual machines and is therefore not related to Windows 7 only.

I have not noticed any changes within the guest O/S C: drives. Both have remained constant. So it is only the pvm files which are increasing.

Note: When initially created Both Virtual Machines were clean builds and not via an upgrades

Surely these increases are not normal? Are we supposed to keep running the compressor to keep some control over the pvm files? If anyone has observed the same or has any ideas why this is, it would be appreciated as I'm at a loss to know what to do.

Kind regards
Kevin