Regression: Firefox 2.0.0.11/2.0.0.20 don't finish the installation anymore.

Official 43407.
I launch the installation it starts and gets more or less to 60%, it stalls there, you see "installing optional components", debuglog shows nothing explorer still responds, I attached to ff and did a backtrace:

kdb:> proc attach 0x228
Attached to process 0x00000228, thread 0x0000022c.
kdb:> bt
Eip:
<ntoskrnl.exe:d6c6 (ntoskrnl/ke/thrdschd.c:396 (@KiSwapThread@8))>
Frames:
<ntoskrnl.exe:10efc (ntoskrnl/ke/wait.c:530 (KeWaitForSingleObject@20))>
<ntoskrnl.exe:a3a89 (ntoskrnl/ob/obwait.c:403 (NtWaitForSingleObject@12))>
<ntoskrnl.exe:ba5f0 (ntoskrnl/ke/i386/trap.s:244 (KiFastCallEntry))>
<ntdll.dll:69c9>
<kernel32.dll:279b8>
<Firefox 2.0.0.11.exe:11a96>
<Firefox 2.0.0.11.exe:12073>
<kernel32.dll:23e2c>
<00000000>
kdb:>