Black screen with blinking Cursor

Tried to delete files on an SD card. Got a non descript error message. Tried to cancel and it hung up. Task manager to end process on explorer. After a min my normal desktop appeared. Got "explorer not responding" when I tried to open a folder. Restarted computer and it took a long time so hard shut down at power switch. On restart it went to dell splash screen for one sec and then the black screen with blinking cursor. Restarting with hitting F2 no change. F12 on restarts just beeps.
Disconnected all peripherals inculding all but one internal hard drive. No Change. Tried Vista disk with no change.

Run the free bootable diagnostics from here: Initial Hardware Diagnostics

Can you boot into Safe Mode?
Can you access the "Repair your Computer" entry on the Safe Mode page (or with the Vista install disk)? If so, run Startup Repair 3 times.
Try System Restore from the Startup Repair menu

If you get into Windows:
- create another "backup" profile and test it
- update all drivers
- scan for malware

The diagnostic lights are 1 2
I removed the only expansion card ( firewire ) with no change.
Then I disconnected the USB cord that goes to the built in USB ports on the monitor. That fixed it! This all started with an SD card not deleting.
Thank you everyone

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Good Luck!