Sorry to hear that, and thanks for your feedback. Which WiFi dongle are you using?
There are some related discussions about WiFi adapter drivers in another thread:
viewtopic.php?f=34&t=423
You may want to check it out to see if it helps.
Another workaround is to use a powered WiFi adapter, such as this one:
http://www.amazon.com/TP-LINK-TL-WR702N-Wireless-Repeater-150Mpbs/dp/B007PTCFFW/
Basically you can plug it into Bone’s Ethernet jack and it provides a WiFi interface to the Bone. This should work pretty reliably.
Regarding your earlier question on having two +5V sources powering the same board, in general you shouldn’t do this. If you want to power Bone from an external power supply only, you can clip off the +5V header pins on OSBo so that it won’t compete with the external power supply. The +5V header pins are number 5 and 6 on P9 (the third column from the right end).
I will have to think about improving the power supply design to make WiFi more reliably for Bone. The 24VAC -> 5VDC regulator circuit is the same on OSPi and OSBo, and it has worked well on OSPi. The Bone probably has higher current or EMI requirements and I will have to investigate further.