After this part, nothing is happening:

* Suspicious files and malware
Scanning for known rootkit strings [ OK ]
Scanning for known rootkit files [ OK ]
Testing running processes...


Also, is CentOS not fully supported? I got this error at the begin of the check:

Determining OS... Warning: this operating system is not fully supported!
Ready
Warning: Cannot find md5_not_known
All MD5 checks will be skipped!

the md5's for CentOS are not supported as far as I know (somebody correct me if I am wrong)

How long have you given rkhunter before you determined that it is stopped during a scan?

An option might be to go ahead and install the latest version of it by hand (not hard at all)

Http://www.rootkit.nl

edited for wrong url

try to run as
"rkhunter --createlogfile -c" and check the logfile, you might find the error there