As I originally posted on patndoris.com back on June 1st, there is the distinct possibility Vista users who install Service Pack 2 will experience a problem with Windows Live Messenger (WLM) no longer launching. Since Service Pack 2 is set to start rolling out via automatic updates on June 30th, I thought it might be a good idea to repost this information again.
Problem: After installing SP2 for Vista, there is the possibility WLM will not launch. Clicking on the WLM desktop icon produces no result. No error. No hourglass. No running process in Task Manager. Nothing. Not even an error that the shortcut points to a program that is no longer valid. Nothing.
I ran into this myself when I updated to SP2 for Vista. It affects both 32-bit and 64-bit Vista systems. It apparently occurs when WLM detects the upgrade to the operating system and attempts an automatic repair but uses the incorrect installer package to do so. This should NOT be a reason for you to avoid installing SP2 for Vista. Service Packs include important security and operating system updates, and the WLM issue is easy enough to fix.
The natural thing to want to do is un-install and re-install. DO NOT! If you uninstall first, you will be prevented from doing the fix. Likewise, do not attempt a repair of WLM either.
Solution: Head over to Live Messenger Download site and re-install right over top of the the existing installation. I did not get any warning that WLM was already installed on my system, and it installed flawlessly in just a couple of minutes.
The problem was officially acknowledged on June 16th in the WLM Support Space blog. Their fix and instructions are basically the same as the ones outlined in my original information.