Do you have a GeForce card? There are certain bad versions of GeForce drivers that cause this problem. This is a problem in the drivers themselves and is unfortunately completely outside our control.
The recommended way to fix this problem is to update your graphics card drivers (go to NVIDIA's web site for this). Alternatively, there is a workaround that alleviates or solves the slowdown problem altogether. Try this:
Right-click on your desktop and select "Properties". Go to the "Settings" tab and click on "Advanced...". Click on the "Troubleshooting" tab and move the slider to the left until it says that all DirectDraw and Direct3D accelerations have been disabled (around the middle of the range). Finally, click on "OK".
Note that this workaround might cause other games on your computer to slow down, so you may have to switch back and forth between settings, but it's certainly worth a try.
Windows XP's "sticky keys" accessibility feature interferes with games that use the Shift keys to fire. You will need to disable it. You can do this either from the dialog box that pops up when you press a Shift key 5 times in succession, or from Start/Control Panel/Accessibility Options/StickyKeys.
Your DirectX version is out of date (you need at least version 7.0). Download the latest version from Microsoft's web site here.
Again, your DirectX version is out of date (you need at least version 7.0). Download the latest version from Microsoft's web site here.
This message says that your computer can't switch to full-screen to play the game. There is no legitimate reason for this (unless you have another full-screen application running in the background). It is more likely a bug in certain video drivers (in conjunction with DirectX 7.0). Try updating your graphics card driver (check your manufacturer's web site) and/or DirectX version (here). Also, before running the game, shut down any instant messengers, and generally any program that may pop up a window. Check the system tray area (at the bottom right of your screen, next to the clock) and terminate any unnecessary programs.
No. (evil laugh)
This only happens with older, zipped (.ZIP) versions of the game. You should download the latest version from this site, which comes with an installer that will properly install the game for you.