Why does my computer continue to try to run a disc (dvd)?

I looked through the questions, nothing seems related. My computer (tower) is homemade (in 2008) by my computer-savvy son, but he lives out of town, not available to help. Computer tower has a place for a DVD. The DVD player was used for a group function - we moved my computer to living room, used another person's flat screen TV. We played a slide show (DVD) and watched a video from internet.

After this event, my computer is plugged back in 'as usual,' but it is extremely slow, especially when it is initially doing some task.

Example:

On start-up, it takes 2-3 minutes to get to the 'Welcome' screen - then another couple of minutes after I 'click' on my User name - (I am the only one who uses my computer, but it is set up this way), and 2-3 more minutes to show my actual 'desktop' with icons. When I 'click' to go to internet (Mozilla Firefox) - that takes yet another 2-3 minutes.

Example:

After starting computer (but have not gone online) - if I want to access a document, I click 'My Documents' icon, and it will take a minute or two - simply to open a stored and saved document.

Same thing happens if I want to compose a new document. It will take a minute or two - just to start or open a new document.

I think that the disc (DVD) driver is broken because:

1) it was used just prior to start of problem

2) the pointer/cursor shows a small silver disc (if I move the cursor) while it is 'trying' to start (above).

I'm sorry, but I do not know many details about my computer. My son built it 'fast' in 2008 in case he wanted to use mine for gaming, (except mine does not have an upgraded graphics card).

Essentially the problem is slowness on start-up (probably related to DVD problem).

My question is: How can I disable the DVD driver - or somehow stop my computer from thinking that it has to play a disc - when there is no disc in the DVD player?

A bit more detail. There is no disc in the DVD player slot. I have tried with door open and closed, no difference in speed. I searched around in the Start Up area for both hardware and for programs, but did not find DVD....

Now the DVD door will not open when I push the button, and when I push on the DVD door, I hear a very faint sound - like a car horn very far away - coming from within the computer tower. Faint 'horn' noise on with light pressure on door, no pressure = no noise.

I think I need to remove the DVD program somehow.

My apology for any vagueness...

p.s. using Windows XP, and M'soft 2007

Ideas?

Thank You!