Dvd-rom not playing/recognizing dvds but plays cds

hi there!!
well after researching my problem on the net all morning, it seems like the problem i have is a very common one but no1 has any definite answers for it! anyway the title pretty much explains my problem, last night i popped in a dvd (that i've watched several times on this laptop) and around the first minute it froze and so i restarted the computer and tried to put in another dvd but even though the computer still recognizes the dvd drive, nothing happens. i tried this with lots of other clean, non-scratched dvds, some copied and some original, all with the same result. i've had this laptop since the beginning of the year and have used it heavily in the last 2-3 months. i tried editing the registry (nothing happened) and i'm too scared to update the firmware yet since i'm a bit of a novice computer user and i've read lots of warnings about how it should be used as a last resort. something else i've noticed, when i go into 'my computer' and click on "DVD-RW" drive (e, it says on the left hand side under 'details' that it is a 'CD drive' when it isn't. i read a post on another website where a person suggested that i may have turned off the service which recognizes the dvd-rom and so it may be recognizing it as a generic cd-rom (which is what i'm thinking now) and theres a way where you can edit the drive specifications so that it reads it as a dvd-rom not a cd drive. does anyone know wot he would be taking about? oh yes, and i'm on windows xp and i haven't experienced any other problems with this computer, it's very random and sudden that this happened! also, i normally use powerDVD but i tried playing dvds on windows media and it hasn't worked so it's not a decoder problem. i'm not really sure if this is a hardware or software issue. i've also put in lots of cds and they work fine. if someone could enlighten me as to how i can fix this problem it would be greatly greatly appreciated!! thanks so much!!
cheers! nanci