Your friend softmodded your box with an Xecuter 2.6? Well gee that's just innovative. I've never heard of anyone doing that.
Having had issues with the infamous FRAG myself (first Xbox blew my TSOP somehow.. even without adding a modchip or anything), my new box has had some issues. Mostly, this is just due to my modchip being finicky, a little piece of dust getting in here, something budging it slightly out of place, etc. my remedy is to unplug it, listen to make sure that everything shuts down (drives, gpu fan, sys fan, etc.), around 2 to 3 minutes, then i plug it back in and it works fine.
however i'm still confused. you say your friend softmodded it, but with a modchip? and then he installed font hacks? if you have a modchip, you don't need any of the font hacks or anything. you can run your very own bios. see some of the tutorials on the site for info on that.
in short, you're just gonna have to try it one thing at a time. you know, pull out the hard drive and boot up with just the dvd drive and see if it'll boot to the typical error screen (08), and then just keep going through until you find something that when you pulll it out, it works fine, and plug it back in, it doesn't work. however, fragging usually means that something is wrong with your tsop chip. so if you have a modchip, just reflash it. if not, get a modchip.