U can get tis problem in old bitmap editors software, not all formats are working with them. Som software have problemm with open screenshots from AH, somtimes its wrong file extension only /jpg - jpga, tif - tiff /. Somtimes u cant open them but u can import.
Just upgrade your software or use conversion software.
When i buy PS6 i think i have this problem from my head, but as time show i need to upgrade them to v.7 quick. And now not get any problems /it was not commercial;)/.
MOst of graphic vievers have good conversion tools, like acdsee 5
Use them to convert and save in other file format, after that try to open in bitmap editor whichone u are use
ramzey