lazy system

at times my system becomes lazy, it wont open the internet expoloreror any thing else. when i try to open things i get a message either the file could not be found or theres no enough resources. only things open already when this happens wil work.
Ive only ever had 1 trojan or virus it was artemis but i removed it and have run several scans with several programs and found no trace of anything left. i have mcaffe avg various products from iobit.com(awsome products and free:P) and malwarebytes. i only download from download.com and i use dap 9.0(which scans after u download).its almost impossible for me to get a virus,so i was thinking some settings were changed by the virus i had,the thing is i dont know where to start to look though. also ive used onlone scans to locate possible infections.if any one can help id appreciate it


also to fix this problem it requires a reboot then it works fine till then it messes up agian.

i have an acer 5251 had it less than 2monthes windows 7 home premium duel core amd also i do have another logon account activated(notsigned in) it has the same password its the to provide a way to remove prsistant viruses/falseor unhonest programs.(helpful too ive used it like that on my moms computer)but it was the guest logon

You should never have two virus scanners active at one time as they will most assuredly slow your system.

Yep, TM is definitely right about that. A helpful link for you to use in safe mode:

AV Uninstallers - Windows 7 Forums

(Hint: Use AVG remover.)

Iobit? Have you scanned for rootkits with Sophos Anti Rootkit? Checked for any suspicious processes with Process Explorer? Possibly created new counters in performance monitor to monitor your system resources?