Computer dvd player

i have 1 computer Asus Dvd Rom model DVD-E616P2 which already use about 8 month ago, but recently when i bought 4 new dvd movie (4 out of 4(not at same time or same shop)) cannot play, some stuck on menu and some cannot play directly.and playing vcd DON’T have any problem also

i have try to installed like slysoft product software name “ANYDVD” also have this problem.

when i check my event log, this was i get

Cdrom Warning None 51
An error was detected on device \Device\CdRom0 during a paging operation

and sometime happen on same dvd

Cdrom Error None 7
The device, \Device\CdRom0, has a bad block.

but when i goto that dvd shop and ask them to try using standalone dvd player , everthing was ok .
and i already “delete” that dvd rom from hardware manager and redetect also same .

for ur information my system was

win2000 sp4
p3 550mhz
256 ram.

thank in advanced.