Registry keys under HKLM/Software/.../Installer/Components/Userdata contain approximately 1,500 data value entries where the colon in the path has been replaced by a question mark (C?\). These registry keys seem to be primarly associated with media file types. The C?\ entries are generated by both Microsoft software (MSXML and MSOffice, for example) and third party software (Adobe Reader, Roxio Media Creator). I spent several hours working with MS Tech support to verify that these entries are present in Windows and were not unique to my computer/installation. After a support person in the Windows Development team acknowledged that the C?\ registry data values were present on his computer, I never heard back from MS Tech Support. The entries continue to be generated with almost every update of MS Office and Adobe Reader. Based on my experience, the C?\ registry data values can (in some cases) cause problems...I initally found the strange data values while trying to resolve problems with Roxio Creator and Adobe Photoelements. The problems (unable to locate file) were resolved by manually editing the registry key data value to "C:\...." I would like to have a better understanding of the significance of the "C?\" registry key data values, but I've had trouble finding anyone who thoroughly understands the System Registry (hopefully they exist!) Screen shots and source counts of the C?\ occurences are available, if anyone is interested.