[Typo3] setup help

[Jane Larsen]

I have som problems with my graphic setup:

I have the following verisons:
GDLib: bundled (2.0.28 compatible)
IM version: 5.5.6 or 6.2.0


Problem is that my png read test shows a blank image (test shows ok though)
and that my thumnails dont work (little squares with red crosses). Cant read 
pdf and AI files but that I can handle, though I would like to read pdf.

Any good ideas for choice (where possible) and settings?

/Jane Larsen