Thunderbird 5 startup crash @ mozalloc_abort(char const* const) | NS_DebugBreak_P | cal::getTimezoneService() caused by lightning 1.0b5 (and newer)

ok heres the Crash ID:

and the description:
Thunder bird 5 loaded this morning to check my mail. I then closed it ( I used to have minimse to tray when closed add-on installed, which 5 got rid off....I'd like make it know that this function is useful, please bring it back!)

I then went to open thunderbird again, took a long time and then brought up the crash reporter window.

I check the crash report contents:
AdapterDeviceID: 9490
AdapterVendorID: 1002
Add-ons: {e2fda1a4-762b-4020-b5ad-a41df1933103}:1.0b4,{972ce4c6-7e08-4474-a285-3208198ce6fd}:5.0
AvailableVirtualMemory: 1905455104
BuildID: 20110624125636
CrashTime: 1312187955
EMCheckCompatibility: true
FramePoisonBase: 00000000f0de0000
FramePoisonSize: 65536
InstallTime: 1311759457
Notes: AdapterVendorID: 1002, AdapterDeviceID: 9490, AdapterDriverVersion: 8.821.0.0
D2D? D2D+
DWrite? DWrite+
xpcom_runtime_abort(###!!! ABORT: Could not load timezone service, brace yourself and prepare for crash: file e:\buildbot\comm-miramar-lightning-release\comm-miramar\calendar\base\src\calUtils.h, line 94)
ProductName: Thunderbird
ReleaseChannel: release
SecondsSinceLastCrash: 23
StartupTime: 1312187954
SystemMemoryUsePercentage: 40

Interesting bit is the "could not load time services"......why not?

I decided that I'd restart the computer, that did nothing and reinstall thunderbird 5, that also did nothing.

Fortunately I can access all my accounts over a web browser, but I use Thunder bird for work to view all my relevant accounts, and this is a little inconvenient for a monday morning!
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