You can try Googling it. It scares me if I can't stop the PC/OS from calling home.

I did a lot of googling, couldn't find anything relevant yet about the GetSyncTransferStatus or similar functions.
I did, however, find a way to hide Skydrive through some registry editing (but I'm not sure it disables it completely), which didn't cancel the crashes completely, but i think it made them less frequent

What do you mean same crash? Same C callstack? With Win32::GUI Tk and Tkx? even if you never call Win32::FileOp?
Yes, same callstack. Or at least it looks like it to me.
This is, for example, the callstack after a crash using only Win32::GUI, using a simple script (like in the OP, only with Win32::GUI) from commandline perl.

ChildEBP RetAddr  Args to Child              
05e6f600 75c66079 05e6f634 05e6f638 0584a6b8 SHELL32!GetSyncTransferSt
+atus+0x5d
05e6f8c4 75a6e121 00000002 05e6f900 00000000 SHELL32!`anonymous namesp
+ace'::_GetItemStatusHelper+0x277
05e6f8e8 75a6e0ce 05e6f994 05e6f900 80004005 SHELL32!CBaseOverlayHandl
+er::_GetItemStatus+0x50
05e6f904 75a6b8b0 0584a6b0 05e6f994 00000011 SHELL32!CBaseOverlayHandl
+er::IsMemberOf+0x1c
05e6f93c 75bed394 05e6f994 00000011 00000064 SHELL32!CFSIconOverlayMan
+ager::_GetFileOverlayInfo+0xa9
05e6f958 75a6e2f6 0069a9f8 05e6f994 00000011 SHELL32!CFSIconOverlayMan
+ager::GetFileOverlayInfo+0x20
05e6fba0 75a6e1b2 00000000 05e6fc64 00000001 SHELL32!CFSFolder::_GetOv
+erlayInfo+0x12c
05e6fbb4 75caa022 04d03b00 00000000 05e6fc64 SHELL32!CFSFolder::GetOve
+rlayIndex+0x21
05e6fc20 75a6ae8f 04c92140 05e6fc64 00000000 SHELL32!`Microsoft::WRL::
+Module<1,Microsoft::WRL::Details::DefaultModule<5> >::Create'::`2'::`
+dynamic atexit destructor for 'module''+0x56c5
05e6fc40 605c2b49 058895f0 04c92140 05e6fc64 SHELL32!CRegFolder::GetOv
+erlayIndex+0x2d
05e6fc5c 605c2ad3 ffffffff 04c92140 00000000 explorerframe!CNscOverlay
+Task::_Extract+0x32
05e6fc78 605b770f 04c91a00 04c92190 00200000 explorerframe!CNscOverlay
+Task::InternalResumeRT+0x32
05e6fc94 75a00665 00c91a00 0000ea60 00696a48 explorerframe!CRunnableTa
+sk::Run+0xab
05e6fcac 759b8a1b 05e6fcfb 00654798 00696a48 SHELL32!CShellTask::TT_Ru
+n+0x2c
05e6fd5c 759b8bc3 020ed3b0 05e6fd78 751f1f86 SHELL32!CShellTaskThread:
+:ThreadProc+0x136
05e6fd68 751f1f86 00696a48 04cc1538 05e6fdf4 SHELL32!CShellTaskThread:
+:s_ThreadProc+0x2b
05e6fd78 77e40e92 020ed3b0 7970f9f1 00654798 SHCORE!ExecuteWorkItemThr
+eadProc+0xe
05e6fdf4 77e3f6c0 020ed3b0 04cc1538 7970fb89 ntdll!RtlpTpWorkCallback+
+0xe6
05e6ff8c 7721495d 00654798 05e6ffdc 77e698ee ntdll!TppWorkerThread+0x4
+87
05e6ff98 77e698ee 00654798 7970fbd9 00000000 KERNEL32!BaseThreadInitTh
+unk+0xe
05e6ffdc 77e698c4 ffffffff 77e5e0f0 00000000 ntdll!__RtlUserThreadStar
+t+0x20
05e6ffec 00000000 77e35658 00654798 00000000 ntdll!_RtlUserThreadStart
++0x1b
[download]

And this is using only Tk, within a bigger program called within an executable packaged with perlapp:

ChildEBP RetAddr  Args to Child              
1800f600 75c66079 1800f634 1800f638 0b34a538 SHELL32!GetSyncTransferSt
+atus+0x5d
1800f8c4 75a6e121 00000002 1800f900 00000000 SHELL32!`anonymous namesp
+ace'::_GetItemStatusHelper+0x277
1800f8e8 75a6e0ce 1800f994 1800f900 80004005 SHELL32!CBaseOverlayHandl
+er::_GetItemStatus+0x50
1800f904 75a6b8b0 0b34a530 1800f994 00000011 SHELL32!CBaseOverlayHandl
+er::IsMemberOf+0x1c
1800f93c 75bed394 1800f994 00000011 00000064 SHELL32!CFSIconOverlayMan
+ager::_GetFileOverlayInfo+0xa9
1800f958 75a6e2f6 002c65c0 1800f994 00000011 SHELL32!CFSIconOverlayMan
+ager::GetFileOverlayInfo+0x20
1800fba0 75a6e1b2 00000000 1800fc64 00000001 SHELL32!CFSFolder::_GetOv
+erlayInfo+0x12c
1800fbb4 75caa022 0b3847a8 00000000 1800fc64 SHELL32!CFSFolder::GetOve
+rlayIndex+0x21
1800fc20 75a6ae8f 08a02538 1800fc64 00000000 SHELL32!`Microsoft::WRL::
+Module<1,Microsoft::WRL::Details::DefaultModule<5> >::Create'::`2'::`
+dynamic atexit destructor for 'module''+0x56c5
1800fc40 61c12b49 089bf188 08a02538 1800fc64 SHELL32!CRegFolder::GetOv
+erlayIndex+0x2d
1800fc5c 61c12ad3 ffffffff 08a02538 00000000 explorerframe!CNscOverlay
+Task::_Extract+0x32
1800fc78 61c0770f 08a05ef0 08a05788 00200000 explorerframe!CNscOverlay
+Task::InternalResumeRT+0x32
1800fc94 75a00665 00a05ef0 0000ea60 003128e0 explorerframe!CRunnableTa
+sk::Run+0xab
1800fcac 759b8a1b 1800fcfb 00265ed0 003128e0 SHELL32!CShellTask::TT_Ru
+n+0x2c
1800fd5c 759b8bc3 0abbf8b0 1800fd78 751f1f86 SHELL32!CShellTaskThread:
+:ThreadProc+0x136
1800fd68 751f1f86 003128e0 089dfc88 1800fdf4 SHELL32!CShellTaskThread:
+:s_ThreadProc+0x2b
1800fd78 77e40e92 0abbf8b0 e94ddd00 00265ed0 SHCORE!ExecuteWorkItemThr
+eadProc+0xe
1800fdf4 77e3f6c0 0abbf8b0 089dfc88 e94ddf78 ntdll!RtlpTpWorkCallback+
+0xe6
1800ff8c 7721495d 00265ed0 1800ffdc 77e698ee ntdll!TppWorkerThread+0x4
+87
1800ff98 77e698ee 00265ed0 e94ddf28 00000000 KERNEL32!BaseThreadInitTh
+unk+0xe
1800ffdc 77e698c4 ffffffff 77e5e0e8 00000000 ntdll!__RtlUserThreadStar
+t+0x20
1800ffec 00000000 77e35658 00265ed0 00000000 ntdll!_RtlUserThreadStart
++0x1b
[download]

As for your suggestions, I'll try using Dependency Walker and give you the results, this will take a few days, as I had to give back the pc I borrowed...

thanks a lot