Seems as if that popular tweaking app Schaps Advanced Configuration program and perhaps other GSM-based "tweak" apps (e.g. Diamond Tweak) might be causing a nasty side effect on CDMA (Sprint & Verizon) phones.
Problem: Ever had an incoming phone call and when you answered it lagged big time?
Turns out that this occurs when you have an active data connection. In theory, the phone should immediately shut that connection and you should be able to answer the call instantly. And it does...unless you inadvertently change some registry settings, specifically ones related to "force data disconnect".
If that value reads ~GPRS, you have a problem; Its should be set to #777 (a least for Sprint users). While manually editing the registry is probably the best way, Juggalo_X created a .cab file which may work for some. Remember to wait about 10 seconds and then soft-reset to take effect.