Random system freezes (possibly browser related)

Hi.

I'm running Win 7 Ultimate x64 on the following machine:

Gigabyte P55-UD3L Motherboard
Intel Core I5-760 2.8 GHz
2x 2GB Kingmax DDRIII 1333 MHz
2x Western Digital Caviar Green Power 500GB Hard Disks in RAID0
Gigabyte ATI Radeon HD 4850 512MB graphics card
Asus My Cinema PE620 TV Tuner
and some low cost wireless card.

I've put the system together about a week ago (all components new) and ever since I installed Windows on it, I've been experienced random system freezes while using my web browser.

Basically the system stops responding for 15-20 sec(sometimes I get mouse movement but not always) and then comes back to normal. At first I thought it was a bug with the web browser (I was using Firefox at the time) so I uninstalled it and installed Google Chrome, but I've been having the exact same problem with it as well.

Any help in solving this matter would be greatly appreciated.

Thanks for answer. I didn't get the time to do a clean boot or a virus/malware scan yet, but I've managed to get a freeze outside using browsers, while copying some data from an external hard drive.

I looked at the Event Viewer and I got two types of errors.
first one is Disk (The driver detected a controller error on \Device\Harddisk0\DR0.)
second one is JRAID (The device, \Device\Scsi\JRAID1, is not ready for access yet.)