ic-klass, my friend just bought the ACRyan PlayOn HD big version with the fan. Was at his place when he was setting it up and he too was curious to know if the fan would be noisy after reading some reviews on it. So we were testing the quality of some full HD 1080 video for about 30 mins and checked to see if the fan was noisy. We could hardly hear anything at all.

YSLYSL, it could be some sort of data corruption either physically with your hard disk or some cross link files etc. This is common with PC's and laptop hard disks and we basically run a check disk to fix the problem (most of the time). So since the AC Ryan PlayOn HD also uses a hard disk, it may very well be suffering from the same problem. Does your unit get very hot btw?