LED/Debouncing problems

OK understood now. you mean:

any one button pressed => AND/OR/NAND/NOR work opposite

two buttons pressed => all work

Sounds difficult now, is your timing ok. I know it is slow clk but you shouldn't ave timing problems. Is your slow clk made global.

I suggest you make cnt(24) enable, thus use fast clk on the process but add:

if cnt(24) = '1' then....

instead of using cnt(24) as clk.

edit: you need to make cnt(24) as one clk pulse