Not long ago I had the good luck of a slow and a normal speed laptop to compare like yours. Both did have issues so I booted up a hard disk test app from CD and let them begin scanning the HD on each machine.
The normal speed machine was reading the drive as a very good clip and the slow machine was lagging badly.
Let me explain that we did not use Windows since we booted from CD so that removed any effect of drivers or other things.
We slipped in a new HDD and the speed returned. The old HDD passed all diagnostics but was still slow. Go figure what was wrong with it,.
THAT'S ONE IDEA.
Next is to read http://forums.cnet.com/7723-6122_102-510824.html where we popped the hood to see what's installed with HIJACKTHIS.
Do you know what each line is doing in your HIJACKTHIS LOG?
Bob
my Dell inspiron 1545 with vista os works extremely slow; use about 6hrs or more to install an application that would have normally taken 3mins.
I've used restore point, check disk error, defragment also uninstalled all antiviruse and all other applicaations that could be the cause but still nothing instead it's become worse. i uninstalled my modem software and now it's no more runninig after the new installation so i can't even access the internet for support or downloads neither can i update my antiV to scan for virus.
it's as though the more i think i'm solving the problem, the worse it gets.
i'm presently totally confused.
What is the problem and what do i do?

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