My laptop runs Windows 7 Home-Premium and it has recently begun to behave strangely at start-up. The operating system itself will load relatively quickly, but there are problems. The Network Icon, which displays how you are connected to the internet, will remain with the blue loading circle for around two or three minutes - even though the laptop itself is connected to the internet (Chrome works). Microsoft Security Essentials does not also activate immediately. It says it is turned off and you can't even turn it on (red icon displayed). Then, after a minute or two, these two will both turn on and be normal. I have ran anti-virus scans, checked for malware, disabled start-up programs that aren't needed and so on. The laptop runs really quick otherwise, but this issue is becoming a real bother when starting. Any ideas? I'm desperate!

System Specifications:

Acer Aspire 5552

4GB DDR3 RAM
AMD Athlon P320 II X2 Dual-Core 2.1Ghz
500GB HDD
ATI Mobility Radeon HD 4250

Does Task Manager identify any programs or services that are hogging resources?

No. I can't open it. It seem as though Explorer itself is lagging, because the Start Menu and stuff is all slow - yet opening apps from the desktop and stuff is fine.