Is there any specific reason you want RealPlayer 10 installed (it is known to take many resources and contains adware and has known vulnerabilities)?
Real Alternative is just that - an alternative to actually having/needing RealPlayer installed.
If you really need RealPlayer, I recommend uinstallling both RealPlayer and Real Alternative, then only reinstall RealPlayer and see if that works.
Again, if you don’t need RealPlayer, uninstall it, then only install Real Alternative. It will play pretty much all real media.
