I'm still stuck with this. Here's the crash report for anyone that understands one.
Process: prl_client_app [1789]
Path: /Applications/Parallels Desktop.app/Contents/MacOS/prl_client_app
Identifier: com.parallels.desktop.console
Version: 10.1.2 (28859)
Build Info: Parallels-28859.1093492~10.1.28859.1093492
Code Type: X86-64 (Native)
Parent Process: launchd [213]
Responsible: prl_client_app [1789]
User ID: 501
Date/Time: 2015-02-06 21:55:09.778 +1100
OS Version: Mac OS X 10.9.5 (13F34)
Report Version: 11
Anonymous UUID: E5EF7D52-1EAC-C368-8575-38D2A1528882
Sleep/Wake UUID: 55DBC078-0A93-472D-BC68-2474600CCCEF
Crashed Thread: 6
Exception Type: EXC_BAD_ACCESS (SIGSEGV)
Exception Codes: KERN_INVALID_ADDRESS at 0x0000000000000088
VM Regions Near 0x88:
-->
__TEXT 0000000106b7a000-000000010a308000 [ 55.6M] r-x/rwx SM=COW /Applications/Parallels Desktop.app/Contents/MacOS/prl_client_app
Thread 0:: Dispatch queue: com.apple.main-thread
0 libsystem_malloc.dylib 0x00007fff8ed41fcb nano_size + 36
1 libsystem_malloc.dylib 0x00007fff8ed40f24 free + 64
2 QtCorePrl 0x000000010d596d22 QMapData::continueFreeData(int) + 66
3 com.parallels.desktop.console 0x000000010759cd43 0x106b7a000 + 10628419
4 libsystem_c.dylib 0x00007fff8bcc47a1 __cxa_finalize + 177
5 libsystem_c.dylib 0x00007fff8bcc4a4c exit + 22
6 com.parallels.desktop.console 0x0000000106b87c3b start + 59
Thread 1:: Dispatch queue: com.apple.libdispatch-manager
0 libsystem_kernel.dylib 0x00007fff94ed3662 kevent64 + 10
1 libdispatch.dylib 0x00007fff8e08d421 _dispatch_mgr_invoke + 239
2 libdispatch.dylib 0x00007fff8e08d136 _dispatch_mgr_thread + 52
Thread 2:
0 libsystem_kernel.dylib 0x00007fff94ed2e6a __workq_kernreturn + 10
1 libsystem_pthread.dylib 0x00007fff93f33f08 _pthread_wqthread + 330
2 libsystem_pthread.dylib 0x00007fff93f36fb9 start_wqthread + 13
Thread 3:
0 libsystem_kernel.dylib 0x00007fff94ed2e6a __workq_kernreturn + 10
1 libsystem_pthread.dylib 0x00007fff93f33f08 _pthread_wqthread + 330
2 libsystem_pthread.dylib 0x00007fff93f36fb9 start_wqthread + 13
Thread 4:
0 libsystem_kernel.dylib 0x00007fff94ed2e6a __workq_kernreturn + 10
1 libsystem_pthread.dylib 0x00007fff93f33f08 _pthread_wqthread + 330
2 libsystem_pthread.dylib 0x00007fff93f36fb9 start_wqthread + 13
Thread 5:: com.apple.CFSocket.private
0 libsystem_kernel.dylib 0x00007fff94ed29aa __select + 10
1 com.apple.CoreFoundation 0x00007fff8df48a03 __CFSocketManager + 867
2 libsystem_pthread.dylib 0x00007fff93f32899 _pthread_body + 138
3 libsystem_pthread.dylib 0x00007fff93f3272a _pthread_start + 137
4 libsystem_pthread.dylib 0x00007fff93f36fc9 thread_start + 13
Thread 6 Crashed:
0 QtCorePrl 0x000000010d566ab0 QThread::start(QThread:

riority) + 80
1 QtCorePrl 0x000000010d64fab4 QProcessEnvironment::systemEnvironment() + 7924
2 QtCorePrl 0x000000010d608afe QProcess::start(QString const&, QStringList const&, QFlags<QIODevice::OpenModeFlag>) + 878
3 QtCorePrl 0x000000010d60af8e QProcess::execute(QString const&, QStringList const&) + 78
4 com.parallels.desktop.console 0x0000000106db1513 0x106b7a000 + 2323731
5 com.parallels.desktop.console 0x0000000106db0907 0x106b7a000 + 2320647
6 libsystem_pthread.dylib 0x00007fff93f32899 _pthread_body + 138
7 libsystem_pthread.dylib 0x00007fff93f3272a _pthread_start + 137
8 libsystem_pthread.dylib 0x00007fff93f36fc9 thread_start + 13
Thread 7:
0 libsystem_kernel.dylib 0x00007fff94ecea1a mach_msg_trap + 10
1 libsystem_kernel.dylib 0x00007fff94ecdd18 mach_msg + 64
2 com.apple.CoreFoundation 0x00007fff8defcf15 __CFRunLoopServiceMachPort + 181
3 com.apple.CoreFoundation 0x00007fff8defc539 __CFRunLoopRun + 1161
4 com.apple.CoreFoundation 0x00007fff8defbe75 CFRunLoopRunSpecific + 309
5 com.apple.AppKit 0x00007fff8e26905e _NSEventThread + 144
6 libsystem_pthread.dylib 0x00007fff93f32899 _pthread_body + 138
7 libsystem_pthread.dylib 0x00007fff93f3272a _pthread_start + 137
8 libsystem_pthread.dylib 0x00007fff93f36fc9 thread_start + 13
Thread 6 crashed with X86 Thread State (64-bit):
rax: 0x00007fff7a8ee420 rbx: 0x0000000000000088 rcx: 0x0000000000000000 rdx: 0x0000000000000000
rdi: 0x000000010d810720 rsi: 0x0000000000000007 rbp: 0x0000000112144a30 rsp: 0x0000000112144950
r8: 0x000061800044bc70 r9: 0x0000000000000000 r10: 0x000000010d80fd60 r11: 0x0000000000000000
r12: 0x0000000000000000 r13: 0x0000000000000007 r14: 0x000000010d810720 r15: 0x0000000000000003
rip: 0x000000010d566ab0 rfl: 0x0000000000010206 cr2: 0x0000000000000088
Logical CPU: 6
Error Code: 0x00000004
Trap Number: 14