[Audax666]

Ok, slept one night over and could fix the IE and Firefox display problem.
I just changed in the forumhome_album_picturebit template the following code.

Take this

<img class="page" src="$vboptions[bburl]/$picture[thumburl]" alt="$picture[caption_preview]" border="0" style="padding:$stylevar[cellpadding]px; <if condition="!$usercss">border:solid $stylevar[cellspacing]px $stylevar[tborder_bgcolor]</if>" width="$vboptions[forumhome_album_picture_width]" height="$vboptions[forumhome_album_picture_height]" />

And replace ist with that

<img class="page" src="$vboptions[bburl]/$picture[thumburl]" alt="$picture[caption_preview]" border="0" style="padding:$stylevar[cellpadding]px; <if condition="!$usercss">border:solid $stylevar[cellspacing]px $stylevar[tborder_bgcolor]</if>" <if condition="$vboptions[forumhome_album_picture_width]">width="$vboptions[forumhome_album_picture_width]"</if> <if condition="$vboptions[forumhome_album_picture_height]">width="$vboptions[forumhome_album_picture_height]"</if> />

So if no width or height attribute is given, it doesen't appear in the code and everything looks fine!