If you setup your CNFs wrong and for example make FMCB boot ule when you power the PS2 this way:
Then your FMCB card will show the FMCB splash screen fine, load and so but then it will look for boot.elf on slot 1 ... Having FMCB on slot 2 will have the effect you described here. So when doing FMCB setup push square for maping the file on both slots (it will look on both slots for the file)
That's one of the things that may cause your problem.
SCPH-10000_GH-001 SCPH-15000_GH-003 SCPH-18000_GH-008 SCPH-30001_GH-005 SCPH-30000_GH-016(V4) SCPH-30001_GH-010(V4)
2xSCPH-10190, 2xSCPH-10350, 2xSCPH-10280
"**** j0 hackers!"
-Sjeep (As seen on TOXIC OS ELF...)