CS3: HDR Merge Problem with Canon 50d RAW files

Question

I recently upgraded from a 20D to a 50D.  I'm running CS3 under WinXPpro with 3GB of RAM.  HDR merge of 3 CR2 files is causing CS3 to generate a program error and crash.  This never happened with my older (smaller) files from the 20D.  Anybody know how to fix this?
TIA,

Answer 1

The suggestion was to try an HDR with smaller 50D sRAWs as an *experiment* to see if the size matters more than the camera model.  Another benefit of a 50D would be the 14-bits per pixel instead of 12-bits and an sRAW would have less noise per pixel than a full-size RAW so using smaller sRAW images might work better than a 20D's.
The "size" being referred to is the dimensions in pixels, not the on-disk size, becasue the in-memory size of an image should be similar whether it comes from a 16-bit TIFF or an 16-bit RAW conversion.
Merging RAWs will involve ACR during the HDR process, whereas merging TIFFs won't unless you have the setting to prefer ACR for TIFFs, too, which you don't indicate.
There can be data in the highlights and especially shadows from a RAW that gets thrown away when it's converted to TIFF, so merging RAWs is better than merging from TIFFs.
I currently have CS4 only on my machine so I forget, but with CS3, does it matter what output size you have set in ACR, when you do an HDR conversion from RAW?  In other words, does HDR using ACR ignore the output size or not?  If not, then perhaps setting a smaller size in ACR (the same area where you set the bit depth and conversion colorspace) would make things work or setting a larger size with 20D images would make them fail.  This is being suggested as a experiment as well, to try to isolate the issue, not necessarily a permanent solution.
I don't think there is anything inherently wrong with a 50D RAW that would make it not work, but the larger size would use more memory and maybe your machine is getting close to some sort of limit.
Other suggestions would be to reset your preferences and check your disk(s) with scandisk and/or change your scratch-disk to somewhere else to make sure there's no some corruption keeping the HDR process from working with the larger 50D images, and along those lines, also try purging your ACR cache or moving it to another drive.  You might also try changing the amount of memory available to Photoshop (ram vs scratch-disk) in the Preferences.
What module does the crash occur in, if the error says?  Is it related to display or something else?