Steam closes automatically upon launch?

[ADragonCalledGeorge]

So I have never had many problems with Steam even though I've got an old PC (Windows XP, Intel Dual Core 2.0GHz, 4gb of RAM, Radeon HD 7750 - used to be Nvidia GT 210). In fact I can run many games ranging from good old Skyrim to the Witcher 2 and even possibly Assassin's Creed 4 Black Flag if the required specs are to be believed. However, as of last night and today I have had an incredibly annoying problem. My issue is that for some bizarre reason Steam exits two minutes after launch. I can't sign into the steam website from Google Chrome because it says my login is incorrect despite the fact that I just successfully changed my password on my dad's laptop. It works fine there though I didn't try playing any games. Thus, I know my account isn't hacked thank god.

 

However, it still won't work on my PC. Steam did a survey of my PC too earlier so maybe they thought my PC wasn't good enough? Is it because it still has Windows XP and they finally stopped letting people use Windows XP for Steam? It's run just fine before and I don't know what to do. I can't post this thread on Steam for obvious reasons and I didn't know where else to post it so I thought I would try here, maybe Tom's Hardware forums. I scanned my PC with AVG Antivirus (free version) and my PC is clean though I do have tons of pop up adds and the like which is really annoying. Could my Steam be infected? I tried uninstalling it and reinstalling it but that didn't help either. I am at the end of my rope and would hate to lose access to all my games that I spent so much money on. Please help!!!

Many thanks in advance!!! :)

[ADragonCalledGeorge]

P.S. Latest update, it seems to be working now but no guarantee that it will continue good like this. Maybe it was a server overload? Or I had too many games installed at once? Either way, fingers crossed and I hope it stays fixed. Dunno what went wrong but I'd appreciate some advice if this happens in the future.

[FMod]

The Steam client doesn't get infected, it has online self-checking.

 

Don't get it the wrong way, but Steam has its own support forums - forums.steampowered.com. You're likely to get much better answers to your questions there.

 

The only way anyone here would be able to provide as much info is if they researched it themselves, likely from the very forums mentioned above, so you can as well skip the middleman.