TxRx lights stay on, not recognized by computer

Last night i was using my arduino just fine. this morn i plugged it in, and was only using the +5v and GND pins to connect to an RC car to try and make it move. I got it to move but i think i destroyed my arduino bc my computer began saying usb device not recognized and when i try to update the drivers(from local folder) it wont let me, just says "best software already installed".
Like the subject title says, when i plug it in, all that happens is i the PWR light, Tx, Rx all stay on, and the L light flashes when i press reset.

Have i ruined my arduino duemilanove?

computer is hp dv6365us running win7 64 bit(has been same setup whole time ive had arduino)

what exactly were you doing that you think hurt the hardware? you could try programming it directly using the ICSP pins. I ordered a programmer for mine on ebay just to have on hand incase I do need it one day.

I wonder.. can the programmer be used with stand-alone atmel chips? (I mean just the chip, without the arduino board.)

Im not quite sure what happened but I tried re-doing what i did and it seemed to get it back to normal..i guess i just threw it into some weird loop or something. dont know how or why but ill try to avoid doing it again.