Updated about 1 yr, 3 mths ago (July 27, 2023). Know a better answer? Let me know!

Negative delta time!

Experiencing the error “Negative delta time!” when playing Unreal Tournament or a game based on its engine, on a dual-core processor, and/or under Windows XP/Vista?

Solution

To fix this:

Right click on the main game application. The location of this will vary from game to game.
- For Unreal Tournament, this will be an application called UnrealTournament.exe, in a folder called System, in the folder you installed Unreal Tournament.
- For Unreal Tournament 2003, this will be called UT2003.exe, in the same location.
Choose the Properties option.
Click on the Compatibility tab on the menu that appears.
Put a check mark in Run this program in compatibility mode.
In the drop box underneath choose Windows 98/Windows ME.

If you are using an AMD processor, you may also want to get the Dual Core Optimizer from http://www.amd.com/us-en/Processors/ ... 18,00.html, which should also correct this problem.

For those curious, this is a result of unsynchronised time stamp counters in multi-core processors, and is normally not a problem as Windows handles this, but some games bypass the Windows API and directly access processor functions for performance reasons.