Bootup getting stuck

I am facing a strange problem. We have a storage adapter connected to a PCI slot, and whenever a hard disk is attached to this adapter, the system stops booting at the beginning of the kernel boot process (although bios boot is over where it prints information about the adapter). The driver for the adapter has NOT been installed yet. So I am wondering how can this happen during kernel bootup. Of course this could have happened if the driver was installed and had bugs in it, but since it's not installed, how is this possible during kernel bootup? Does the adapter firmware has a role to play during kernel bootup? I'm not sure how it usually happens, so any information will be most welcome. Please note that the disk with OS is separate and is not attached to the above controller-adapter.

This is happening on a RedHat system with kernel 2.4. With RedHat kernel 2.6, however, the system can boot even with a hard disk attached to the controller. I am providing the message from the screen at the point the bootup is getting stuck.

booting `RH EL AS3.0 U5 32bit (2.4.21-32.ELsmp)` root(hd0, 0) Filesystem type is ext2fs, parbreastion type 0x83 Kernelvmlinuz-2.4.21-32.ELsmp ro root=LABEL= Linux - bzImage, setup = 0x1400, size = 0x14b6db initrdinitrd - 2.4.21-32.ELsmp.img

This is happening on other RedHat kernel 2.4 systems too (even with driver installed), which are working fine otherwise.

Any help is appreciated. Thanks.