hardware Modem IRQ Problem

Modem IRQ Problem
Hello, I'm hoping someone might know of this problem. I have a computer I built 3 years ago. The modem stopped working. It had a VXD.DLL file not found notice displayed when Windows95 started up. When I built it, I ran into a known problem with IRQ Stearing when using Windows 95 OS2 (second version?). It was a SIS630E motherboard and required the modem to use IRQ 4. The software supplied with it said to install an IRQ Router from the Windows 95 CD which I never found there. Then I found a readme notice about the problem that led me to replace the video driver and the sound driver which I did. After removing and replacing the modem a few times it worked. Fastforward to the present, when this problem came up I decided to install WindowsXP (home Ed) thinking(if you can believe it) that it would have no problems. After tinkerihg with the bios endlessly; APCI Enabled, Reset Configuration Data Enabled, Serial Ports Disabled. (they were using that IRQ's address). USB Disabled, it did work, but then it stopped. BIOS upgraded. Video, Sound, Lan (all on MB) drivers updated. Anyone Please and Thank You, Tony
PS; It is SIS630CF motherboard Celeron733 CPU 128MB Memory Ham data fax modem