The VDS is crashing while using the VDS Backup/Restore feature.
While clicking the start backup button, the server displays a warning message that the VDS will freeze and then you can download the backup. However, from that moment the account isn't accessible anymore.
The source of the problem is in the impact of the Information Bar.
This new feature of Internet Explorer 6 and SP2 is blocking popup windows and it is enabled by default. After the Backup/Restore popup screen was blocked, the session number is not equal to the tar file, and this causes the VDS to stay in freeze status.
In order to prevent this from reoccurring, it is necessary to permanently enable popup for the site (PVDS) or disable Popup Blocker feature (Information bar). In both cases this should be done before logging into the VDS in order to backup/restore it.
Popup Blocker feature can be found in the Tools -> Privacy screen of Internet Explorer.