DVD Burner not working in Mac Mini

My mac mini (running OSX 10.7.5) all of a sudden stopped burning/reading DVDs, however CD burning and reading still works.

I ran my system's disk utility and corrected some problems and tried again to no avail. I tried a previously burned DVD which did not work either. However, after trying several DVDs, I got the burner to work (or at least it appeared to as it went thru the usual messages of recording my iDVD movie, but when the recording message showed DONE, the screen appeared to freeze there (typically, at this point, I usually get a message that asks if I want to burn another) --I was able to hit cancel to exit the program. Anyways, the DVD did not burn. At this point on the plus side, I can now read my previously burned DVD... so I tried again to burn my iDVD Movie again but it just spits out after 15-30 seconds.

I saw on some boards that I should try cleaning the burner? Do I have to take my system apart to do this? Do I use a cleaning disk? If this is the case, will my DVD acknowledge it if it isn't working? Or do I just spray compressed air into its slot?

Any help would be greatly appreciated as this is for a job that I need to get out.

Thanks so much!