none of the mods work on fresh install :(

I have just installed 7.3 on a fresh domain and installed several mods but when you click on the links nothing shows up, at first I got a server error 500 but tech support changed some thing in the .htaccess file so it now worked but nothing actually works now, please help.

 Is it an auto installer?

no it was a manual installation, upload files and follow install process only thing wasn't straight forward was setting file permissions of the INC directory, according to the install it was writable and should have been unwritable but the folder was actually set to 0755

 You will need to remember that in the future for upgrades.

When I went from an older version, I had changed the /inc folder to 555 as per the install information.

Later on during a particular upgrade the file set included /inc files which of course didn't get written. That caused an upgrade failure and had to do a total site restore; starting again making sure the /inc was writable. 

Have fun with...