Maximum PC

First things first, Am not a NEWBIE! Am not a GEEK! I do not need to know what everyone needs to know about RAM settings !

Am here seeking help with a problem that I've encountered re-installing Win 7 Ultimate on a mulitboot system with Win Xp pro.

I was an early adopter of Sandy Bridge, I invested in a Gigabyte P67A-UD7 motherboard which I had configured with a RAID 10 setup between 2 OS's, Win xp pro and Win7 Ultimate.

Last week I got my replacement board through Newegg, the GA-P67A-UD7-B3 board.

The steps I took in rebuilding my system are as follows;
1. Backed up important files to another hard drive. Gone online to download new drivers for replacement motherboard, made of a Floppy for SATA Drivers for Win xp.
2. Deactivated all such programs that need deactivating.
3. Through the BIOS on the original P67A board, I had gone into the Intel RAID setup program and converted the RAID drives to NON-RAID.
4. Replaced original board with replacement GA-P67A-UD7-B3.
5. Configured BIOS with same settings as old configuration.
6. Gone into Intel RAID setup and configured drives for RAID 10.
7. Installed Win XP pro, installed drivers with new set that were downloaded PRIOR to getting my internet connection setup, installed Bit defender 2011 program minus updates.
8. Rebooted and got Win Xp up with new drivers, plugged in Ethernet cable and got a connection, downloaded new updates for security. SYSTEM stable.
9. Updated Win XP with all Microsoft updates for said OS. As far as I know, am confidant that am good to go.
10. Inserted Win 7 DVD, booted into and configured it properly, no internet connect yet, updated drivers with downloaded drivers, installed Bit defender.
11. Rebooted and as before, I believe that I had a STABLE system before internet connect and updates.
12. Updated with all Microsoft updates, updated Security software , rebooted at least 2-3 times to be sure system was stable.
13. Installed Firefox 4 and things went to hell in a hand basket !

Problem, As soon as I gone online with Firefox4, I started having problems with the same type as long ago, IRQ conflicts. That's what it seems to me at least.
I would get mouse unresponsiveness, jerky mouse movements, system slowdowns and sounds quitting. I had a hard time in rebooting through the system so I had to do a Hard reset. I DID ALL my normal troubleshooting procedures and I still have this problem.

I can not tell if it's a Hardware issue or if it's a combination of issues.

Does anyone have any suggestions ?

Win XP Pro 32bit with SP3
Win7 Ultimate 64bit with no SP1 update as yet.

Did you load the 64 bit version of Firefox?

http://www.start64.com/index.php?option ... &Itemid=75

Nasty