Merging multiple pdf files

Experiencing recent problem with merging multiple pdf files. The end file has alternating black (similar to film negative) and white pages.

I uninstalled 0.9.9 and loaded 0.9.8 but same results.

TIA for your help.

I did a pretty good video tutorial of merging docs in pdfcreator a while ago.  It may be worth a look.

I tried to access but was blocked by user/password requirement. When attempting to register, was informed "User registration is currently not allowed".