I would suggest doing a complete removal of the Delta drivers, and then going back to using the older 5057v3 driver if you can.
Alternatively, if you have System Restore turned on, you may be able to roll back to an earlier time when the older driver was still working.
Core 2 Quad Q9400-Scythe Ninja Rev A|MSI Neo P45|WD 150GB Raptor|WD 250gb SATA-I|8GB G-Skill DDR2|WD Blue 640GB SATA-II|Logitech KB|Apple Mighty Mouse|ATI HD4850 512MB-Accelero S1|M-Audio 2x Delta 1010|Delta 66 Omni I/O|Corsair 400W|Cooler Master Elite 330
Dual Boot: Ubuntu 10.04 x64 Lucid/Windows 7 Home Premium x64
Adobe Audition Mac & PC, Logic Pro, Ardour, PT 9, Reaper x86 & x64, Ableton Live Lite
2x Delta 1010, 2x Delta 66, AP2496, FW Solo, Pulsar II, ProFire 2626, Fast Track C400