Well, it's pretty much up to you...what your next step is. The advantage that you have over anyone at this forum...you actually have access to the system and can perform checks and such...whereas we cannot. We can guess, suggest, etc...based on the data you provide...but you are in much better position to determine what you think is wrong...and correct such.
If you want to check out your RAM via a diagnostic tool, you can do that.
Memtest86+ - Advanced Memory Diagnostic Tool - http://www.memtest.org/#downiso
MemTest Manual - http://hcidesign.com/memtest/manual.html
Outdated, but basic guidance on how a user should proceed.
Icrontic » Diagnose with Memtest86+ - http://icrontic.com/articles/diagnose_with_memtest86
If you want to check your hard drive via a diagnostic tool, you can do that, using the tool provided by the respective hard drive manufacturer.
Hard Drive Installation and Diagnostic Tools - http://www.bleepingcomputer.com/forums/t/28744/hard-drive-installation-and-diagnostic-tools/
If you suspect that malware is an issue (HJT is a tool for handling malware issues...not a general purpose troubleshooting tool...you can follow the procedures established at BleepingComputer.com - Am I infected What do I do - http://www.bleepingcomputer.com/forums/f/103/am-i-infected-what-do-i-do/
And...you can check Event Viewer for any possible indications of errors (not information items) which might impair system functioning.
How To Use Event Viewer - http://www.bleepingcomputer.com/forums/t/40108/how-to-use-event-viewer/
You referred to the number of mouseclicks it takes to do something...have you simply tried a different mouse (along with everything else, they too can go bad)?