Computer freezing and driving me mad!!

[Chickadee]

Please can anyone assist? Upgraded my broadband late last year and shortly after my PC's (desktop and laptop) kept freezing when going onto the internet. The would happen numerous times. Contacted broadband provider who were about as much help as a chocolate teapot!! Anyway, I uninstalled the browser software and reinstalled it and everything ran fine for a while. But I an getting the same problem again. The only thing that has changed is the I have uninstalled Norton antivirus software and downloaded Avast antivirus (after reading lots of recommendations on here).
My desktop PC only freezes now and again but the laptop freezes practically everytime.
Both are running Windows XP with service pack 2. As well as Avast they both have Spybot and Windows Defender.
Can anyone help please as I am at my wits end!! Thank you and apologies if this question has been asked before but I am new to this site.

[Androcles]

You say you uninstalled Norton - it is one of the most sticky programs known to man - I don't know if that is the problem, but I had some similar difficulties and found that Norton had not gone away and was interfering with other anti-virus programs. Check this out: http://www.askdavetaylor.com/how_can_i_fully_r emove_norton_antivirus_from_my_system.html

It might help.

[RaidingWolf]

I can tell you this much, I had a problem with Norton. On Symantec's site there is their own tool for removing the program cleanly here:
http://service1.symantec.com/SUPPORT/tsgeninfo .nsf/docid/2005033108162039

Hope this will help!!