I use Norton Systemworks Pro, it's very good.
It's now owned by the Symantec corporation.
It has six major utilities built into it:
It has Norton AntiVirus.
It has Norton System Doctor.
It has Norton Win Doctor.
It has Norton Disc Doctor.
It has Norton Speed Disk.
It has Norton optimization Wizard.
The System Doctor and the Win Doctor would catch many problems that could cause the symptoms you described and automatically fix them for you.
It costs about $39 in stores like CompUSA, BestBuy, and Circuit City, or you can get it from the Symantec Website, at a non-discounted price.
I've used them for about 8 or 9 years and have a lot of confiidence in them and I purchased a copy for both of our computers.
The Norton Antivirus is a top notch program also, and it needs to be kept updated about twice a month. The Systemworks pro has an automatic update feature that when you're connected to the Internet, it will check it's own website and retrieve new versions when they're available.
A very good product and I recommend it without hesitation.
hope that helps