I have the same card with Win98SE. It is a pain to get working.
If all you want are the drivers, these work.
http://www.vogonsdrivers.com/getfile.php?file … menustate=43,36
If you want the entire software package, I do recall finding one single Liveware install CD that supported the CT4780. I believe it was this one.
http://www.vogonsdrivers.com/getfile.php?file … menustate=43,36
If you are running it on a VIA chipset, I'd also strongly encourage the VIA PCI Latency "Patch"
http://www.vogonsdrivers.com/getfile.php?file … &menustate=29,0
Edit: You know what, I got the CT4780 which I have confused with the CT4870 you have. Regardless, your issue sounds identical to the issue I had, so these specific drivers might help?
Win95/DOS 7.1 - P233 MMX (@2.5 x 100 FSB), Diamond Viper V330 AGP, SB16 CT2800
Win98 - K6-2+ 500, GF2 MX, SB AWE 64 CT4500, SBLive CT4780
Win98 - Pentium III 1000, GF2 GTS, SBLive CT4760
WinXP - Athlon 64 3200+, GF 7800 GS, Audigy 2 ZS