SoulseekQT crashes within seconds of opening.

After starting SoulseekQT up it crashes within seconds, always with the "unexpectedly quit" message. The error details are as follows.

Process: SoulseekQt [209]
Path: /Applications/SoulseekQt.app/Contents/MacOS/SoulseekQt
Identifier: com.yourcompany.SoulseekQt
Version: ??? (???)
Code Type: X86-64 (Native)
Parent Process: launchd [72]

Interval Since Last Report: 222 sec
Crashes Since Last Report: 1
Per-App Interval Since Last Report: 11 sec
Per-App Crashes Since Last Report: 1

Date/Time: 2012-11-10 19:21:14.299 -0800
OS Version: Mac OS X 10.5.8 (9L31a)
Report Version: 6
Anonymous UUID: F081211C-21B7-4637-9467-35A852A1719E

Exception Type: EXC_BREAKPOINT (SIGTRAP)
Exception Codes: 0x0000000000000002, 0x0000000000000000
Crashed Thread: 0

Dyld Error Message:
Symbol not found: __ZSt16__ostream_insertIcSt11char_traitsIcEERSt13basic_ostreamIT_T0_ES6_PKS3_l
Referenced from: /Applications/SoulseekQt.app/Contents/MacOS/SoulseekQt
Expected in: /usr/lib/libstdc++.6.dylib

Thanks so much for your help on this!