i hope i removed my q-tip this morning BEFORE i left home .

but back to my problem:
i'm confused. thanks alot for helping me, stryder. as described before i used different formats. i tried tga, jpg and dds, too. when using dds i cared for the "power of two" format, i created mip-maps i saved in format DXT1-RGB (no alpha-channel, cause my textures don't have any transparency). i used the plugin version 5.67 on paint shop pro 7.
and why could i make my own working textures with exactly the same config a few days before?

i really appreciate your help! i've got the feeling i just need the one deciding kick into the right direction to solve this riddle myself.

i have to ask...are you certain that you created your texture as a power of 2 and NOT a multiple of 2?

thank you for replying stryer,
i understand that you have to ask this. but i can assure you that my textures are certainly scaled by the power of two (some are 512 x 256 oder 256 x 512 and some are 256 x 256).
update: i tried paint shop pro 8 (psp8) with the newest version of dds plugin (version 6.6.0827) of developer.nvidia.com. tried psp8 and saved textures as 24 bit tga uncompressed -> no change, tried psp8 and saved as jpg standard encoding with 10% compression -> no change.
slowly i'm getting depressed