Can't program board! Usb failure

Development Tools IDE 1.x
1

So my Arduino has been working fine up until today. I had plugged a IR sensor into digital 2(I'm new to electronics and I'm still trying to figure this out..)....and I'm starting to think it was a very bad idea.

My board lets me program it once, maybe twice but then when I try and reupload something I get a message on the debug that says:

avrdude: usbdev_open(): did not find any USB device "usb"

Did I mess up?
Any help appreciate

the ir sensor i was using was http://www.sparkfun.com/products/241

I had my 5v coming out the board into my bread board.

The 5v from the bread board went into a 10k resistor and from there went to the anode of the IR Sensor

I read on the arduino website that the arduino has a ADC and the sparkfun website said to use a simple ADC so I plugged it into the digital 2.

Also, not sure if its related but a friend but a voltmeter on either side of the IR sensor while plugged into A0 and the board seemed to reset.....

Any ideas

2

I plugged my UNO into my windows XP computer, as compared to the vista one I was running earlier, and I now get AVRDUDE: stk500_getsyn(); not in sync: resp=0X00

AHHH!

Sorry for reposting so many times, this is why people hate noobs....

I got the com port right on my XP and now can upload code from it.

But, this is a but of a set back....I wanted to use my laptop for programming. Guess its not a huge thing, but if anyone can help..