This is a weird one. Never had this happen before. And what seems to have triggered it was installing the Guitar Tracks Pro 4.0.5 Update. Whenever I try to start a new project, I simply get nothing. No tracks window. And yet GPT4 tells me that there is a project open. The middle of the screen is totally grey as if there is no project open. Now let's say I create a project called 'test', and the screen is totally grey, and then I try again to create a project named 'test', it will then tell me I can't create another project of the same name of the one that's open. And yet nothing is open. I go up to the file menu and there is no "close" option as there is normally when a project is open. I'll illustrate with screen shots.
 
This is what I see after I start a new project.

 
I scratch my head, thinking maybe I made a mistake hit a button wrong, so I try to create the same project again, and get this:
 

 
Ok so now I'm really confused. So I figure if a project is open why can't I see it. I'll go to the file menu and try to close it, and restart the whole process, but there is no project I can close:
 

 
Now one other thing that seems like it could be related is that before the patch if I opened an old project, the tracks window would be full screen like this:
 

 
Now when I open old projects, this is what I get:
 

 
Anyways, this doesn't seem like a problem, at least I get a tracks window. Not being able to start new projects because the tracks window is missing is a bit of a problem...

When you tried to open a new project, did you select a Template? It looks like you opened the standard 'Blank-No Tracks or Buses' template.
 
As for the old projects being minimized, that happens to me sometimes even though I had the screen maximized the last time I played with it.
I just maximize it again and continue.

57Gregy
When you tried to open a new project, did you select a Template? It looks like you opened the standard 'Blank-No Tracks or Buses' template.
 
As for the old projects being minimized, that happens to me sometimes even though I had the screen maximized the last time I played with it.
I just maximize it again and continue.

 
Actually, no, I did not open a blank template, I opened the normal template which puts bass, drums, guitar, etc...But FYI, you are wrong, this is not what the screen looks like (the first screenshot) when you do the "Blank" template. The blank template still has the tracks window, just no tracks added yet. I know because I normally always use the blank template.
 
Here is what "Blank (no buses or tracks)" would look like (I got this screenshot by opening an old project and deleting everything):
 

 
Notice in the above screenshot, there is a second window open, in addition to the program itself, with it's own minimize, maximize and close button (upper right corner). This second window should be present even in the "blank" template. This is the mysterious missing window that has disappeared completely. I double checked and this bug happens with: 16x4 mixer, 16x4 mixer (blank), Blank (no tracks or buses), & normal. But it does not happen with: 24x8 mixer, 24x8 mixer (blank) ---- these two still work and open the tracks window as normal. Just for ease of comparison and so you don't have to scroll up two pages, here again is what I am seeing (using "normal" template):
 

 
Notice there is no second window open, in the upper right corner there should be a second minimize, maximize, & close button. Also, there is no way to add tracks to this screen. Normally, I would left click in the dark grey area (in the first screenshot) and a menu would open and I select add track. Left clicking on this bugged screen does not give me the menu to add a track. The "add a soft-synth" button is greyed out and cannot be pressed either. And yet, as I explained and show with screens in my first post, the program thinks there is a project open, and won't let me start another project with the same name.
 

Were you experiencing any of the issues that the 4.05 update addresses?
If not, I would suggest rolling back to the point release version of GTP4.
System Restore is your friend sometimes.
It would appear that the update is not agreeing with your video drivers.
The tip-off is that you are getting a void onscreen where some sort of image should be presented(ie: the blank template). As you've noted, the program thinks there is a project open. You just can't see it.