To sum things up for everyone else:
trv said: If you had searched the forum, you'd have seen that this was due to microsoft's upgrade in their servers, which ended up affecting all aMSN users. Now, it's only your fault if you thought it was a keylogger and reinstalled everything.
Johnsonbgr said: I was completely panicked because I'd end up losing all my contacts, I really thought that was a keylogger because hotmail told me I was using the wrong credentials even after I changed my password. Anyway, using latest svn now, runs fine. I mostly came here and wrote while I was angry, people must have taken me for a complete idiot but nvm.
chgentso said: You're way too stupid there, I wonder how you even managed to register to this forum. What you said was too stupid even for a person writing in anger.
Johnsonbgr said: Just try to imagine what it would feel like to be about to lose all your contacts - work, girlfriend, friends, family - because everything depends on one single email address... I felt very panicked...
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Now, my answer to Johnsonbgr - in english, in order to make it understandable to the general public here

First, if you only receive a suspicious file and do not execute it, you are safe. aMSN cannot automatically execute the contents of what it is receiving.
Second, if you receive a file and THEN execute it, and it turns out to be a virus, it's not AT ALL aMSN's fault. It's your fault for running things without being sure what they are. Blaming aMSN for a virus you were sent through it is like blaming the post service for a mistakenly overloaded credit card bill. aMSN was merely used to transfer the file, nothing more.
Third, the MSN servers are very well known for their temporary failures, which happen quite too often. You may receive "Invalid username/password" messages again, without you having changed anything. Don't panic, just retry later, the servers are going crazy again. Yes, the "MSN Service status page" will still think that all their systems are stable... If you're feeling unsure, drop by irc.freenode.net #amsn and ask whether anyone else has trouble connecting.
Fourth, don't click on links or open files without asking what they are first. Lately, there are a lot of viruses that spread as a link that appears to come from your contacts. You may catch a virus by just clicking on them. So, if you receive anything, just ask your friend "what did you just send me now?". Also, it's important to NOT let Windows Live Messenger remember your password. Such viruses are able to retrieve your password and then log on using your account in order to send their advertisements to your contacts. This is likely to happen even if you are using aMSN, though I haven't actually confirmed it.