Solved the problem, … 
Today I had time to "play" with my computer.
So I began taking off some Ram as intended. Whith 512MB installed, my system used 400MB Ram. With 128Mb my System used 114MB, ... hmm
Than I began with the Preferences (because I knew from earlier tests that it could´nt be the extentions or the control panels), put them all away, no solution – my system was going on to use to much Ram.
Later I installed a new system from CD at the same volume. The new system didn´t heave that problem, …
So I replaced the Finder, System, System Resources … with the new installed versions. No solution.
And the winner was: my Fonts Folder !
All the problems where caused by a broken Font! Every Apple-Book tells you that damaged Fonts can make really cracy things to your System, but I didn´t think about it. Maybe this informations will help anybody sometimes.
My MacOs is now running with 42 MB in use and everything feels fine again (with installed 1GB).
Today I had time to "play" with my computer.
So I began taking off some Ram as intended. Whith 512MB installed, my system used 400MB Ram. With 128Mb my System used 114MB, ... hmm
Than I began with the Preferences (because I knew from earlier tests that it could´nt be the extentions or the control panels), put them all away, no solution – my system was going on to use to much Ram.
Later I installed a new system from CD at the same volume. The new system didn´t heave that problem, …
So I replaced the Finder, System, System Resources … with the new installed versions. No solution.
And the winner was: my Fonts Folder !
All the problems where caused by a broken Font! Every Apple-Book tells you that damaged Fonts can make really cracy things to your System, but I didn´t think about it. Maybe this informations will help anybody sometimes.
My MacOs is now running with 42 MB in use and everything feels fine again (with installed 1GB).