Have a read through this click here it might be a good idea to download and run Hijack This click here and see if the same type of entries described in post #3 are found in your Hijack This log file. I would post your Hijack This log to the same site along with a description of the problem and ask someone to check it for you before attempting to remove any suspicious entries though.
I've used F-Secure for quite a few years now on various machines and have had no problem with the issues you describe.
I too am a big fan of FSecure. Currently running FS IS2009 on a Vista laptop with 2GB RAM... it flies (it was OKish with 1GB but did cause a noticeable slowdown at times !). What are you running and how much RAM ? If you open the program (IS2009 anyway) there is an option to change the protection level away from "normal" to one more suited to running on a low spec system... although you should not need to do this.
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