Bicycle Tutor

Yesterday, I pulled out my bike after a month of non-use. The tires were flat, so I pumped them up today and I was riding my bike and the rear tire started to skid, it does so randomly. Does anyone have a suggestion as to why this is the case?

By skid, do you mean the rear wheels locks up completely?

I don't think it locks up, but rather just slips of the right then off the left and very random intervals. Like the whole rear end of the bike will slip, and I will hear it doing so and feel it as well.
Maybe another way to describe it is that it pulls hard in either direction.

Does the rim wobble from side to side when you pick up the rear end and spin it in one place? Does it spin freely? Does it feel loose if you jiggle it from side to side?

Doesn't seem like it wobbles and the wheel does seem to be spinning freely. But I did tighten the wheel and reinfalte the rear tire and it seems to have reduced the problem. I went for a bike ride and it now only seems to happen when I make a turn or change lanes. I am just trying to narrow it down now the problem. Could it be the wheel being lose or the tire not being properly inflated (the guage on my pump is broken).
I am also wondering if it could be the brake. The rear brake is tighter than my front brake, so could it be touching the tire just a bit.

It might be an inflation problem. If the pressure is too low the tire could shift while you're riding. It would be worth investing in a tire pressure gauge to be sure.
If you think the rear brake might be causing the problem, lift up the rear of the bike and spin the rear wheel while watching the rear pads to see if they are rubbing on the rim.

So I tried it out again this morning. I put it on a stand and tried to spin it freely and it started slowing down and it stopped randomly. I remember you mentioning something about the wheel spinning freely.
I also notice the wheel was wobbling just a tiny bit. Not much maybe a millimeter or two. You really need to focus on the wheel to notice it.
Any suggestions you could make with that information?

Are you sure your axle isn't moving around?
Check that the wheel is actually aligned properly on the frame. I had a little problem a couple of weeks back I thought I had the rear wheel on right and it was actually off a bit. I didn't ride it for more then a few minutes till I figured out something was wrong. I stopped gave up the intended ride and worked on it till I realized the wheel wasn't actually sitting right.
Now I didn't have any skidding but I noticed I couldn't spin the cranks in reverse without the chain coming off. I turned it over and while spinning the wheel I noticed the resistance at certain points in the rotation. Don't recall what made me decide to check the wheel alignment. But I did check it and after a few tries I found the right spot.
Something to consider too is are your brakes catching as the wheel wobbles and rotates, even if it only seems slight to you. You could see if loosening your brake cable, assuming you don't have disk brakes, to see if that reduces the resistance in the spinning...
Who knows your spokes could be loose too, sounds like it is possible you have multiple issue...

Good news, it appears to be fixed. Looks like that the gauge wasn't the only thing broken on my pump, the pump it self is not pumping too well. I borrowed a friends air compressor for his car and pumped up my bike to 75 psi and it seems to have done the trick.
Now it was raining so it felt like it slipped once when it went over a bump on the road, but I wasn't certain if it was slip. Usually before the slip was quite abrupt and I was certain that was the case. But none the less it does look like the bike is in good working order. I am going to have someone else give the bike a try and see if they notice any slipping just to be sure.
As for the wobble, I took a look at a few other bikes and they all appear to have the same wobble but none of there actually slips. The wobble as I said it not too extreme it was a few millimeters at most.
So it was tire pressure all along, whoops.
Thanks to everyone for there help.