windows 7 - Acer Aspire 8942g laptop running increadibly slow all of sudden

Hi four days ago my computer all of a sudden started struggling with simple tasks, it will take 30 secs just to open notepad, or explorer or basically any task while as before everything was pretty much lightning fast. Havnt installed any new software or hardware, had windows defender update but, like said, tried bacup recovery and same thing even going back 2 months... Have tried system restore, registry cleaners, anti virus, ad ware, malware.....Nothing seems to be showing up in Task manager as well except for sudden spikes that happen continuously, although not showing what it is..... I have win 7Ultimate 64 bit, Intel icore7, q720 1.60ghz, 6gb ram. ATI Mobility Radeon HD 5850 1gb, 640 harddisk,
Please help, cant find anything on what this could be?