I've tried un-installing and re-installing, trouble shooting, other forums, and more. One day it works perfectly and the next only partially. As soon as i click on ADD, the smaller window opens and then goes gray, with "Program no longer responding.", and the only way to close it is through Task Manager's end process. Win7 Ultimate, 64 bit. Thank you for your help and assistance.

In my system, it doesn't crash but very slow. I think Tixati file browsing/navigating has something wrong/not performance friendly. They didn't user Windows build-in elements (Open/Save windows, dialogue,...) but their own style browsing. The ADD function usually slow down program a lot whenever try to use it.

You can read ther:
http://forum.tixati.com/support/264/

Win 7 Pro x64 (AMD 2.20ghz processor - 8g RAM)
Tixati 1.96 x64 version

I just installed and started using Tixati today, and as nnq2603 reports, when I use the +Add (New Transfer) feature and the Explorer process begins, I'm getting a v-e-r-y slow response.  It's not freezing or crashing for me either, just taking way longer than normal/expected to finally get there.  To eventually get to the popup menu is taking average 25-40 seconds.  There is no spike in CPU or system lag, just a long wait.  
Ditto when I click on "Browse for file..." --another 25-40 second wait.  Then, once i begin working my way through drive folders each click takes from 5-8 seconds to process, where Windohs Explorer is usually nigh instant.  Each folder navigation lags as well.
However, when I click the "Browse for folder..." button, the expected popup menu works as expected ie quick.  Even down through the folder navigations.
I have 4 hard drives and the experience is the same with each.
???
Thanks for taking my issue!

BUMP

Have the same problem as the OP. As soon as I click on the 'Add' button, Tixati crashes with the Windows 'Program has stopped responding' error message. Was running an older version when it started happening (never happened before, program worked fine), updated to new version and still happened. Reinstalled Tixati and also still happened.

+1. Also having this problem, whenever I click the "Add" button it takes over 2 minutes to actually bring up the "Add New Transfer" window, all the while tixati is unresponsive.

I reported this back in January - without any luck :-(
https://forum.tixati.com/support/2208/

have you tried version 2.39 alpha-2?

https://testing.tixati.com/

and when it crashes, be sure to send the crash report to the devs. its the fastest way to get crashes fixed.

For any actual crashes yes please send them in.

Unfortunately those are few and far between.
The main problem tends to be how much RAM tixati uses. You don't want to starve it disk bus speed (another way, use a separate drive, or only download to 1 drive, seed to a separate PHYSICAL drive) When you try to multitask too much you can use any process monitor (Task Manager comes with "Open Resource Monitor") to see. Most likely your lags in Tixati are tied to access to your pagefile.sys
There are ways to reduce this, i.e. turn off settings you don't use. But unfortunately the RAM doesn't get reclaimed unless you restart Tixati.

When you are experiencing these crashes go to your %APPDATA%\tixati or ~\tixati folder (unless you run it PORTABLE) to copy/backup your .DAT files.

If you wait for it to clear, you can go to Settings -> IMPORT/EXPORT but .DAT files can be out of date up to 15 minutes if you are interested.

Current settings end in .dat LAST startup (beginning of this session) are .lastloadok.dat .. And while it is backing up (every 15 minutes) the files are .dat.new and .temp