For a quick-fix try, if you have either an ATi or nVidia based video card (or integrated onboard) -- download the latest drivers & see if that helps. Some gaming sites have reported trouble with some of the latest patches -- Civilization V had a patch that cause a msvcr90.dll error, for example (for that error, the newer drivers provide relief).
Is it a new version of RealPlayer that you are installing? The latest version requires that you have Windows XP's Service Pack 3 installed already. If you are behind on your Windows updates, uninstall RealPlayer, download and run CCleaner (both the Cleaning & Registry functions) [--- http://download.cnet.com/ccleaner/?tag=mncol;1
---], visit Windows Update & install Service Pack 3 plus all other important updates, until you are up-to-date. Grab a fresh download of Realplayer, and don't use any "download manager" software to get it -- just download it straight from your browser. Then try reinstalling it.
Scan for malware, too -- since infections can cause system misbehavior. If you find a serious infection, visit our Security forums here at TSF for their help with detecting & cleaning --- http://www.techsupportforum.com/f50/...lp-305963.html
You can also consider using System Restore if all was working well until just recently.
For more clues to any other system troubles you have, take a look in your Event logs. Go to the Control Panel and open the Administrative Tools. You'll see Event Viewer among the tools.
Best of luck
. . . Gary