Quick, name one thing worse than the latest firmware update to the Sony Ericsson Xperia X10 not being to Android 2.x. Stumped? How about the latest update not only keeping the phone at Android 1.6 but also introducing a WiFi bug that proves to be quite the nuisance when located in an area with poor cell reception. Never mind the fact that you probably rely on WiFi working properly most in areas where reception may be poor, if your signal happens to drop down to zero bars then gets wind of a good connection and the bars jump back up, out goes the WiFi. The issue has only appeared in phones that have gone ahead with the R2BA026 update. Our advice would be to simply steer clear of it and wait for a fix from SE.
[Unofficial Sony Ericsson Blog via Engadget]