Everything you need to know about WPC reset issues:
http://techniek.flipperwinkel.nl/wpc/index2.htm#reset
Note: I just fixed the reset problem on my TZ and it was NOT BR2 or C5. It had a bad voltage regulator (Q1 I think). The repair guide recommends replacing C4 with a larger cap, so I did that too (I used a 470uF aluminum electrolytic).