I upgraded my 2G Iphone to 2.2 and then jailbroke it with quickpwn. All went peaches and cream until I did a master clear on the phone (Settings>Reset ALL). It took an hour to complete, and when it was done is when Is when the problem started.

The iPhone is stuck rebooting and only gets to the Pineapple logo before it reboots again. I tried putting it into DFU mode to restore it, but when I try to hold Power & Menu, the phone just turns back on and reboots until I let go of the buttons.

Whats a man to do??

you are not going into the dfu mode correctly ....follow the following steps..:

Get the iPhone into DFU mode. When in this mode the iPhone screen is black.
1. Connect the iPhone and your Mac/PC
2. Shut down iTunes
3. Hold Power/Sleep until the red slider shows up, slide to shut the iPhone down. If this aint work hold Power/Sleep and Home until the iPhone shuts down.
3. Hold Start/Sleep and Home for 10 seconds (I count like 100, 200, 300, ..)
4. Let go of Start/Sleep but keep holding Home until...
5. ... iTunes starts up and finds an iPhone in restore/recovery mode. The iPhone screen is black.