Windows Live Messenger lag

I've had a lag issue for a while with Windows Live Messenger where, at times, it will lag when typing, and at times it becomes unusable. I had this issue with the previous version, and updating to WLE2011 has not helped, in fact at times it has got worse. It becomes more profound when using YouTube and Microsoft Office, but occasionally will happen even after closing those programs and restarting MSN. It uses over 50% of my CPU, and 92-95MB of RAM, which strikes me as being very odd indeed. I don't have any viruses, and the total CPU usage and memory usage is 60-75% and 59-61% respectively. Any ideas?

I uninstalled Windows Live sign-in assistant and that helped initially, but since I have had the same issue.

Also, every time I close Excel or any part of Office 2003 the Office Live Add-in Sign-in crashes - I'm wondering if this is part of the cause? I have no idea why it crashes, but it does every time without fail. And I can't seem to uninstall it - couldn't find the option.

 

How do you know you do not have any virus infection, that would be the first thing I would look for. A visit to our Malware & Virus forum may be a wise precaution.

Looking in the Event Viewer may shine some light on the crashes.

 

How do I know? Because I've run several virus scans both with and without MSN installed, that's how. With two, if not three, different programs - AVG, Avast! and Avira.

Office Live sign-in thingy's error:

"Faulting application OfficeLiveSignIn.exe, version 2.0.2313.0, time stamp 0x491c0a79, faulting module OfficeLiveSignIn.exe, version 2.0.2313.0, time stamp 0x491c0a79, exception code 0xc0000005, fault offset 0x00003ce7, process id 0xe5c, application start time 0x01cba13098877316. "

All of them are exactly the same, except for the process id and start time, which obviously would change.

When behaving properly, it doesn't eat more than 30% of my CPU and only uses 28 MB of RAM, and this is with the same number of windows open - 2.