To be thorough you should test your hardware with these bootable CD tests which will autostart:
RAM - Test with Memtest86+
for 5-6 passes or overnight
boot to run extended test.
Also run Disk Check
from DVD/Repair CD Command Line.
Make a Win7 Repair CD to boot to run Repairs: System Repair Disc - Create
Follow these steps to boot the CD How to Boot your Computer from a Bootable CD or DVD - Boot to CD,
or tap the Dell F12 key at boot to get a one-time BIOS Boot Menu.
Run Startup Repair from the Repair CD several times to check for problems. It should automate System File Checker but run it separately anyway from the CD Command line: SFC -SCANNOW Run in Command Prompt at Boot
When you ran Factory Recovery it should have reinstated the Dell Recovery Partition even if you formatted all partitions. So try Factory Recovery from partition first as it is more stable and doesn't require booting disk, just tapping the F8 key at bootup: Dell Restoring Your Computerīs Software to the Factory Settings
If the Factory Recovery link is missing from F8 menu as shown in tutorial, try restoring it using this method: Dell Recovery Partition - restoring F8 link
After running factory Recovery monitor the logs closely for clues to the problem before it arises again, use the System Resources working through these steps as needed: Troubleshooting Win7