The only thing I can suggest is you check the IBM website to make sure that it is a supported version of the OS. Unless it is specifically supported by IBM, it probably has some known problems with DB2 (like RH9).
A friend of mine have installed DB2 in a linux kernel version I have mensioned above and it works properly. But it is not an x86 architecture. I reffered the error number in IBM support and did what it recommends to do, such as altering the access rights of "/dev/null" and also giving write privilages to "tmp" folder.
Still the same error exists. The other thing I noticed is that there are no db2 services running( using the command ps -fu) in the OS.