Troubleshooting avi playback in VDub help needed for MeGUI encoding.

[thegame]

Hi,
I just had something very strange happen to me and cannot figure out what went wrong, I have an avi file 1280x720p(actually 3) with no audio that played back very smoothly in VDub, I have a Quad Core PC with 8 GB's RAM and 3 500 GB hard drives, OS is Windows 7 Pro 64 bit,but now for a the last week or so they play choppy, and I have NO idea why, and I think it is carrying over to MeGUI when I encode now, first pass would only take little over an hour, then second pass would take quit a bit longer LOL, well now first pass is taking almost 10 hours, my MeGUI settings have not changed, so I am assuming it has something to do with VDub's issue as well, does anyone here have any ideas of what could be wrong and what I can do about it? I need to encode these but I keep aborting because first pass should be fast.

Thanks so much

Edit, it also seems to only be avi files at 1280x720 on my system, 720x480 and smaller play fine, and my avi files use the Lagarith codec, but like I said, just a week or so ago, ALL files played fine, this is confusing.

[AnonCrow]

Do the smaller resolution files take longer/forever to encode too ?
Ruled out overheating and any possible issues with the HDDs ?
If you play or transcode directly with eg. VLC or mplayer/mencoder , choppy playback/forever to encode then too ?
If you view your recent Windows Recovery points, are there any from about a week ago and what programs does it say would be affected ?

[thegame]

Well I know I am not running hot, I have big fans all over this case running full speed, and I have a huge CPU cooler on top of my CPU, and video cards are not running hot either, I keep everything cleaned regularly, but for the heck of it I copied the file from the hard drive that has the file to a different hard drive and it plays fine from the other drive, so I guess this tells me I have a hard drive failing, why else would it play on one but not the other, I guess I better start backing up while I can.

[AnonCrow]

The HDD going bad is a very distinct possibility - if the 3 drives are identical then the S.M.A.R.T. data might show some indications of impending failure.
If the bad HDD already sounds different than the other 2 then that would be an ever clearer indication - unless the 720p lossless video file is just really horribly fragmented.
After making backups, would still try connecting the drive to different SATA ports (I'm assuming they're not PATA drives)

[thegame]

Thanks for the help, but after trying to get everything off it throughout the entire day, and there was not that much anyway, just everything I needed LOL, it would take 4 hours for a 20 GB file to transfer, but hey, at least I eventually got it, but since, I yanked that drive out and replaced, now all is better.