You might want to stay up-to-date with EterniaGame's Crossfire Website, they are talking about custom Xtrap Patches, and completely removing it as an Anti-Cheat Device.
Posted on their site;
i've worked on the patcher system, we can have custom updates now, not exactly meaning that we can edit .REZ files, we can just edit the tga graphics for now, .rez files takes some time of reversing work.
why i stoped working on clans and worked on patch system?, well, i got a way to disable the xtrap
In the meantime you may want to try your average Crossfire help on this error;
1. If you are running Windows 7 you may need to change the comparability to Windows XP
2. Your Anti-Virus Program Or Firewall may be causing a disruption in the normal loading process, You may want to disable these programs temporarily or add them to the "Exceptions List". To learn how to do so I suggest you Google Your Anti-Virus Programs Exceptions List.
3. A program or virus may be altering Xtrap files as they begin to update. Most commonly these programs are MSN, Skype, Xfire - I highly recommend you do not run any unnecessary programs when playing Crossfire. You can close them manually or use a program such as SmartClose to automatically disable these variables.
SmartClose download and reviews from SnapFiles
4. Speaking about the Virus ... You may want to run a thorough Virus scan on your computer - Completely deleting any malicious files and restarting your computer, Best free programs to use;
AVG
AVG Free | Antivirus Download | Free Virus Protection
MBAM
Malwarebytes' Anti-Malware: Malwarebytes
5. Finally and lastly you may need to completely and cleanly re-install, follow this tutorial but changing everything with the
Private server download.
[GAME ERRORS] GUIDE - Performing A Clean Installation Due To Errors - Z8Games
Good luck and remember to check their website for more information on the Private Server.