Strange playback issues...

[VismundCygnus]

I've been thoroughly enjoying my blu ray capabilities for over a month now using Powerdvd 8. however, the majority of the discs i've been playing, i've been encountering a recurring issue. i'll be watching a movie and all is fine and somewhere during, it will freeze up, like would happen with a very badly scratched dvd in the past. problem is these blu-rays don't have a fingerprint on them let alone a single scratch. the only movie i can remember that i don't recall giving me an issue was Underworld. however, Hellboy started freezing around the 12 min mark and wouldn't stop until i moved it to around the 25 min mark. No Country For Old Men began freezing towards the last 1/3 iirc. I just got incredibly frustrated tonight while i was watching The Prestige and it was fine till the 1:16:00 mark and then it froze and kept slowly trying to advance to a playable part but never got there. this makes no sense, the disc is pristine. can someone give me some insight as to why this may be happening? is it the software? i've never been a big pdvd fan, but it seems to be the best at covering all of the codecs so i went for it. any help anyone could offer would be highly appreciated. could it be this blu ray drive? when it plays it plays perfect, but there's always that 'oh no' feeling when it screws up and seems to stop being able to read the disc...so here's my specs:

Antec Solo Black/Silver Steel ATX Mid Tower Computer Case
Seagate Barracuda 7200.11 ST3500320AS 500GB 7200 RPM SATA 3.0Gb/s Hard Drive
SAMSUNG TOC T240 Rose Black 24'' 5ms HDMI Widescreen LCD Monitor
GIGABYTE GA-MA790X-DS4 AM2+/AM2 AMD 790X ATX Ultra Durable II AMD Motherboard
SAPPHIRE 100242L Radeon HD 4850 512MB 256-bit GDDR3 PCI Express 2.0 x16 HDCP Ready CrossFire Supported Video Card
Antec True Power Trio TP3-550 550W ATX12V Power Supply with Three 12V Rails - Retail
OCZ Platinum Revision 2 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory
AMD Athlon 64 X2 6000+ Windsor 3.0GHz Socket AM2 125W Dual-Core Processor Model ADX6000CZBOX
ASUS 2 Tone Blu-Ray Combo SATA Model BC-1205PT
using my old M-audio Revolution 7.1 as well...
on Windows XP SP2
Power DVD 8.0.1830.50

thanks in advance...

-Vizzy