Don't know if you're still having problems with Realplayer, have you tried the newer version Realplayer 10? I had a problem with one of my pc's and had to follow this to fix a playback problem:
"When you try to play a video, Windows may display Invalid Page Faults, or your RealPlayer may crash or show distorted video such as:
- an empty magenta or black square;
- a snowy, static-filled picture that moves;
- a video with a green tint that is distorted;
- video with stripes in all or part of the screen;
- video that is stretched vertically or horizontally in one direction, making the picture look long and flat, or tall and thin.
These problems occur when your computer is using a video card that does not understand the instructions that RealPlayer is giving to it. You may be able to resolve this problem by:
- setting your video display to 16-bit color;
- updating your video card drivers;
- installing the latest version of DirectX;
- lowering the hardware acceleration of your card;
- disabling optimized video in RealPlayer.
Solution 1: Set your video display to 16-bit color.
RealPlayer requires 16-bit (65,000-color) color depth. If the video card is not capable of this, you will receive an error message when you start RealPlayer that requests that you increase the video resolution.
To check your color settings:
1. Click the Start button, point to Settings, and then click Control Panel (Windows XP: Start > Control Panel).
2. Double-click the Display icon.
3. Click the Settings tab.
4. Select 16-bit, 24-bit, or 32-bit from the colors list.
5. Click OK.
6. Restart your computer if prompted.
Solution 2: Update your video card drivers.
Video cards use driver software to send information from the computer to the video card. Drivers that are out-of-date, damaged, or not DirectX-compatible can cause video problems. Update your video card drivers, and visit the video card manufacturer's Web site to verify that you are using the latest DirectX-certified drivers.
Solution 3: Install the latest version of DirectX.
DirectX is another set of drivers that to send information from the computer to your video card. RealPlayer uses the DirectDraw features of DirectX to optimize the video presentation. DirectX is a component of the Windows Operating System. If the DirectX components are out-of-date or damaged, RealPlayer may crash or display the video incorrectly. Install the latest version of DirectX from http://www.microsoft.com/directx.
Solution 4: Lower the hardware acceleration.
Choose the appropriate procedure for your operating system:
1. Right-click a blank area on the computer desktop.
2. Select Properties, then the Settings tab.
3. Click the Advanced button, then the Troubleshoot tab.
4. Move the Hardware Acceleration slider to None or one notch away.
5. Click OK twice.
6. Restart your computer.
Windows 98SE, ME, 2000:
1. Click the Start button, point to Settings, and then click Control Panel.
2. Double-click the System icon.
3. On the Performance tab, click the Graphics button.
4. Move the Hardware Acceleration slider to the Basic or None level.
5. Click OK.
If the problem no longer occurs after changing this setting, leave your system on this setting. If it does not resolve the problem, set it back to where it was. The Basic or None setting is more compatible than Full in most cases, but setting it at Basic or None disables some advanced features of the video card.
Solution 5: Disable optimized video.
If you have tried the solutions above and are still having problems playing video, they may be caused by a video card that uses WinDraw drivers instead of DirectDraw drivers. Disabling optimized video in RealPlayer will improve compatibility for video cards that are not DirectDraw compatible.
To disable optimized video in RealPlayer:
1. On the Tools menu, click Preferences. The Preferences box opens.
2. In the Category pane, click Hardware.
3. In the Video Card Compatibility section, drag the slider to Most reliable.
4. Click OK.
5. Close RealPlayer and restart the computer."
I suppose if its the newer RM files causing problems on your HD you could always try as a last resort converting the clips to another format using RM Converter, it still requires Realplayer to be installed, but you can make RM's into AVI's with it.