MSN Messenger 7.5 can't sign in

During morning, had this irritating problem in office, my MSN Messenger (Build 7.5 0299) just can't able to sign in, not matter how i tried. At first i thought it was my Panda Platinum 2006 Internet Security Antivirus firewall which has blocked it or MSN Messenger service is down. After did some troubleshooting myself, discoverd that my other colleagues has no problem signing in! How strange! Found out that those using MSN Messenger 7.0 are able to sign in with no problem. Read up some thread on forum and realised that MSN Messenger 7.5 has 'bug' , anyhow forced to install 7.0 to kill the problem.
Update info: MSN messenger has came out newer version " MSN messenger 7.5 (Build 7.5 0311), hopefully it fixed the bug.