itimer "run-with-idle-timer" signaled: (error "Invalid timer")

[Stephen J. Turnbull]

Adam Sjøgren writes:

 >   itimer "run-with-idle-timer" signaled: (error "Invalid timer")

Does http://tracker.xemacs.org/XEmacs/its/issue547 look familiar?  If
not, please give more description when you have better information on
reproducing the error.

Anyway, try upgrading to at least version 1.18 of the fsf-compat
package (latest is 1.19 which is preferred).