Hung up on boot screen (HP Pavilion)

My system - HP Pavilion Desktop P6310f, AMD Athlon II x4 630 2.8GHz, 6gb ram, GForce 8600GT, 1Tb HDD (new installed 12 mnts ago), Win7 64bit installed by a vendor. When I got it home, I created 3 Recovery DVDs.
System have worked fine. Uninstalled a program today, that I do not use and did a START/REBOOT.
Problem - hung up on the blue HP screen with the hand and several apps icons flowing to/from the hand.
Four options shown - F10=Setup, Esc=Boot Menu, F11=System Recovery and F9=Diagnostics.
Keyboard not active, no response from any key or combination of keys such as Ctrl/Alt/Del.
Experience - Not a total nubie, can follow instructions to chase down issues.
Did a hard boot by unplugging the pc, plug it back in and press the power button. Hangs up at the same screen.

Did some search on this site, but all relate to BSOD. Any help appreciated.
Thank you in advance.

I searched the web for possible solutions and read a few threads. Ended up doing the following.
1. Unplug external devices other than mouse & keyboard. Mine where parallel printer (via usb port) and my router.
2. Power on and booted fine.
3. Clicked on Start/Restart and booted fine.
4. Clicked on Start/Shut Down, reconnected the router, power on, booted fine.
5. Opened browser, go on a couple of sites and all is fine.
6. Clicked on Start/Shut Down, reconnected the printer, power on and hung up.
7. Unplug power cord from the back, disconnect printer, power on and booted fine.
8. Clicked on Start/Shut Down, reconnected the printer in different usb ports (total 3 ports), power on and hung up.
9. Unplug power cord from the back, disconnect printer, power on and booted fine.

Printer: HP LaserJet 2100 which worked fine before in the win7 os.
Any one have any feedback?
TYIA.