Strange cut out at the end of my song

In a new song I've been working on, every time I export it, there is a strange cut out at a consistent time in the song. I worked on the problem for hours and what I discovered is that when I disable track automation when I export it, it works fine. But when I deleted all my non-essential envelopes, it still didn't work. I also attempted exporting a previous project with just as many tracks, and it worked fine. I am honestly stumped. Can anyone help me out?
 
I have a Dell 64 bit Inspiron (brand new) with Windows 8, M-Audio mobile-pre mkII and SONAR Home Studio 7 XL. 

Ok so I did and I found out that the only track that actually cuts out is my lead guitar track. When I muted it it worked fine and when I crop out just before the part where it cuts out it works (which I can work around with a little reverb). So the problem should be fixed. But can someone explain to me how this could have happened? Cause I don't understand why this happened at all, but I'd like to for the next time this happens.

I have had similar problems after I purchased a new bundle of VSTs which use a bespoke audio engine. Even with only two tracks in the project, one of the tracks kept cutting out; and when it wasn't cutting out, it was adding in notes I hadn't written! Maddening! The only solution was to split the project into three sections at the cutout points, 'bounce to track' each section and then 'bounce to track' the three .wav files to create a single wav file. The makers of the audio engine tell me it is a known problem and they are "working" on it! The VST bundle cost hundreds of pounds - am I happy - guess!
 
Sorry Songman - just letting off a bit of steam! You may want to check the VST / amp sim / etc with the suppliers or perhaps have a look in their forum (if they have one) to find out if anyone else has had problems with that product (that is how I found out I was not alone in being unhappy!).  You might also want to check your RAM usage. When I 'bounce to track' to create a composite .wav file of a project, my system regularly warns me that Home Studio 7 is using a huge amount of RAM and CPU processing. How large is the project and how many effects do you have on the miscreant track? It may even be a mis-performing effect on the track.