Iexplore.exe and avp.exe high cpu usage

Hi
First of all hello to all.
My problem is with iexplore.exe and avp.exe.
To be more specific whenever I'm using the internet, iexplore.exe runs in 2 instances (is this normal?) and can be using up to 200.000k between them.
My pc runs Windows XP SP3 version 2002 (fully updated autmotically).
The processor is an Intel Pentium Dual CPU E2140 @1.6Ghz with 1Gb of RAM with 1536Mb pagefile size (I'm a bit of a novice at this - just in case someone assumes I'm knowledgable in this field!)
This slows everything down to a crawl to the extent that mouse and keyboard inputs are totally ignored by my pc and everything seems to grind to a halt.
I regularly get the "this program is not responding" message - usually when I'm in the middle of something important! :cry
On top of this, I have Kaspersky 2012 (full purchased edition - not a freebie) and avp.exe keeps running twice, again with exceptionally high cpu usage with the same results as the iexplore rubbish.
I've run Kaspersky FULL scan and MBAM has also done a full scan and nothing was found! :banghead

I have had this problem for several weeks and have been unable to find any help so far as I have read so many different opinions as to the cause.
I have NOT run any of the on-line "FREE" fixes /registry scanners etc because I do not trust any of them!PLEASE PLEASE HELP ME before I go totally nuts. :flip