Morten: Thomas is telling me that he only added debug output and suddenly it works again. Can you try to reproduce the exact steps you took to compile? Were you rebuilding, building all, workspace, only one target, or what? What exact variables were you replacing, and what values did they have? What project were you trying to compile? (CB? what revision?)
The time you were writing this I was already asleep... I hope you guys had some sleep, too. :shock:
I can confirm that it is working by now.

I've done another update today in the morning where the only file that was updated was macrosmanager.cpp. Doing a "build all" (of the C::B workspace, NewBuild) with this updated file everything is working.
However: With the interim-build of yesterday evening I was refering to I could have had also the problem as described in
http://forums.codeblocks.org/index.php?topic=1674.0 since I am using global variables, too. I could imagine that I was faced this error instead of custom variables one... The build log is so big and the result would have been the same (a linker error). Sorry for the confusion.
Morten.
P.S.: Because you were asking: I have setup a path to a special lib in the compiler custom variables properties: "RAPID_LIBS=D:\Devel\RAPID\libs". This path I have setup in the directory settings for the linker of my project: $(RAPID_LIBS), that's it. The value was still assigned in the compiler setup but the compiler/linker output showed an empty "-L" entry in the log. Maybe for the future a testcase-(dummy-)project could be setup that depends on 1.) a global variable, 2.) a custom variable setup in the compiler settings, 3.) a custom variable setup in the project settings...