Slow/Unresponsive on Startup

I bought my laptop 2 years ago and I never really had any problems with it, but for the last couple of months it started to take much longer after logging in. Before the problem, it would take approximately a minute (or less than that) to go from the log in screen (where it asks you for your password) to being fully started up. But then it suddenly increased to 10-15 minutes (I hadn't installed any new software or anything), after logging in, explorer (explorer.exe, not IE) would be slow and you can hear the usual Skype signed in sound but it would take another 5-10 minutes for the Skype window to appear. After that it runs perfectly normal. I then de-fragmented the disk, cleaned up, removed software I don't use, performed disk checks, memory checks, scanned registry, performed virus scans plenty of times. The scans didn't show any errors. The de-fragmentation, etc, helped, it now takes about 5 minutes to start up (when I hover over the Windows Taskbar the normal select cursor changes to the busy cursor). Again, after those slow 5 minutes, it runs normally.

System details below
Please help

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Tech Support Guy System Info Utility version 1.0.0.2
OS Version: Microsoft Windows 7 Home Premium, 64 bit
Processor: Intel(R) Core(TM) i5 CPU M 480 @ 2.67GHz, Intel64 Family 6 Model 37 Stepping 5
Processor Count: 4
RAM: 3950 Mb
Graphics Card: ATI Mobility Radeon HD 5470, 512 Mb
Hard Drives: C: Total - 465872 MB, Free - 264357 MB;
Motherboard: Sony Corporation, VAIO
Antivirus: Kaspersky Internet Security, Updated and Enabled