Unfortunately, the crash report is not very helpful.
I tried to reproduce it locally, putting the system to sleep multiple times, but the tweaker doesn't crash on my PC.
Do you have a way to reproduce it?
Also, does it crash if you turn off the update checking feature?

Thanks for the dump, but unfortunately, it doesn't contain much useful information.
The crash happens in a callback. I assume it's caused by the update checker, but I can't tell for sure.
Do you have a way to reproduce the crash?

P.S. might be a duplicate of:
http://tweaker.userecho.com/topic/382920-after-wak...

Wouldn't it be more logical for Rainmeter to provide such functionality?
Anyway, what you want is the "Reserve empty space on taskbar" option, but with a customizable width?

Great :)
Also, one more hotkey Windows provides by default is Shift + Left click.

Works correctly for me on Windows 7 x64:
http://imgur.com/a/zShXk

Note that this option doesn't have effect on a vertical taskbar.

Should be fixed in v4.4.5.5 beta.

Currently, Windows 8.1 Update 1 (and the equivalent server version) are not supported. I believe you're using some sort of leaked/beta version?

Seems like a duplicate of:
http://tweaker.userecho.com/topic/382920-after-wak...

Please, provide a crash report.
How do I find event logs when a program crashes?

Please see my reply here:
http://tweaker.userecho.com/topic/308231-cycle-bet...

Yes, it works only for the main taskbar.
I believe that adding support for the secondary taskbars isn't worth the complexity.
First, the secondary taskbars have a different mechanism that limits the width.
Second, the tweaker will have to remember the sizes of all available taskbars.