Please help - no boot unless all ext. off - is this soft/hardware problem?

[Escapee]

Hi Folks,
Here's how it went:
Installed a PCI card in my beige G3 mac, third party card.
Started up mac - no problem, eveerything running fine except card was incompatible!
Shut down.
Removed PCI card.
Started up - freeze. - Will start(sometimes) with extensions off otherwise freeze.
Cannot see error code at freeze, as window appears but is blank.
Cannot start from OS 9 CD unless extensions off. - does this mean it's a hardware problem?

Have tried resetting NVRAM, PRAM, CUDA, ended up wiping drive but still no joy!?


Please help