Also, are you running any security software like Norton, McAfee, etc. or a firewall other then Windows? Trying to get a handle on this and was thinking if you saved IM to Desktop, then booted into Safe Mode to install it. Or, if you can enter Safe Mode with Networking to do all of the un-installing, running CCleaner, downloading/installing IM, and it works afterwards, it may mean there was a conflict somewhere with everything that gets loaded in normal boot up.
You are not the only one that has had this problem and I am surprised the VIP Help service hasn't responded properly. I would keep after them listing the original error report you received the first time. I have a problem with the Spell Checker after clicking Send and cancelling it. It is a Registry Key problem I'm trying to track down to change the value.
Post back on the results if you can go through all this again in Safe Mode.