Sorry i can't help you ..
But i have the same issue on my Vario III (WinMo 6.1)
The only thing that i can put this down to was installing the updated version of the latest version of Windows Live ...
Have you found anything yet?
I tried M$ and they suggested that it was a problem with T-Mobile - but i (and i am sure that you) know that this isn't the case.. because for 1 - its the same if i download via wifi .
I know it has been almost a year since you have this problem and you probably already has solved it by hard resetting. Anyway... Since I got here looking for the very same problem on my omnia and today I have solved by simply deleting the PocketFS.sys file on the root directory (don't worry, WinMo will recreate this file during the boot).
After that, all items on my remove program list have been restored. I can install cab files once again, and I didn't tried the activesync, but I guess it will work as well...
and I didn't had to hard reset my omnia!
Good Luck for the other who has googled this problem