I don't know about the freezing problem, but I usually just hit the Start key. It stay with the GTA VC intro screen, but I wait and it goes back to the desktop. then I click on the GTA VC application on the task bar
For the mouse however
1.Turn on compatibility mode to Windows 98 for GTA VC application
2. If you have MTA:VC make sure to set The MTA 0.5 compatibility to Windows XP (Service Pack 2)
You're set
If the mouse acts up again during gameplay
1.Pause the game
2. Press the "Resume Game" option with the keyboard and move the mouse vigorously
3. It should work