I am using Minecraft 1.6 and Forge 1.6. I do not have a launcher and I am not using a patcher. When the mods folder is empty, all is harmony in Minecraft, but whenever I put a mod in (I have tested with five mods, all of which the creators say work with Forge) I get a classnotfoundexception error.

 

Here is a Minecraft error test log: http://pastebin.com/tPe5b7LL

 

Here is Minecraft's own crash report: http://pastebin.com/Z2eHrzfr

 

Here is the Forge crash log: http://pastebin.com/MhvQBif5

 

I've tried reinstalling Forge, redownloading the mods, contacting the mod owners (they don't understand), updating Minecraft, deleting minecraft.jar, and crying helplessly and none of them have worked. I'm sorry if the solution is obvious but I am seriously confused.

Update Forge.

I've tried using Forge 1.7 but then I get a fatal error as it is apparently incompatible with Minecraft 1.4.6. 

java.lang.ClassNotFoundException: pamsmods.common.Pamclayspawn

Not a forge issue. Cleanup your folder, and remove the mods causing issues.

You evidently didn't read the part where I explained that this happens with every mod I've tried, and the mod creators have not had any reports of problems from anyone else. It clearly is a forge issue.

I read that part and applied my vast bank of experience and first hand knowledge of the code to realize that you're in fact wrong.

Its a installation issue, one or more of the mods you have installed is screwed up.