Again is their a bone stock K version of firmware I can download and install some place?
Again, CHDK does never intentionally modify the area of ROM that contains the firmware, so even if you could find a way to re-flash the firmware (which you can't, unless canon has released a firmware update for that camera), it most likely won't solve your problem. It is theoretically possible that CHDK could "accidentally" write to this area, but it's hard to imagine what sequence of events would lead to this (calling the right function by random chance is highly improbable), and it is likely the effects would be more drastic than what you've reported if it did somehow happen.
You determine whether firmware has been modified by dumping your camera and comparing it to a known dump. However, the canon firmware does routinely modify onboard "ROM". There are (at least) areas used for a log and for storing camera settings, so you cannot simply compare full dumps. If you want to compare the firmware proper (code and static data) you need to exclude those areas. If you want to pursue this, some people here might be able to provide assistance. I would suggest getting a full dump and posting on some file hosting site as a start.
If this is actually a CHDK problem, it should probably affect all users with this firmware version, or the subset who have done whatever sequence of actions you have done. Because of that, it would be helpful if you could describe as much as possible what you did when you had CHDK installed. I.e. what features did you try, did you run particular scripts, which exact build did you use, etc.
edit:
If you want to resolve this problem, you need to provide more information.
How are you reading the files ? By USB, card reader or both ?
Which software does not recognize the files ?
Is the camera otherwise functional ? That is, does it capture and display images without problems ? Does the camera itself show the 1970 dates ?
If you manually copy the files from your card, can a regular image viewer (irfanview, picasa, windows image viewer, or whatever runs on your OS) view them ?