Well regsrv32 is a way to (re-)register the executable in the Registry, though it didn't work for you I doubt that even if it ran it would have changed anything.
The "No DOS or PE signature found. This is not a valid 32-bit or 64-bit Windows module." is "queer", the .cpl files are renamed .dll's (hence the possibility to run them via RUNDLL32), that DW should "understand" just fine.
It should mean that *somehow* the actual timedate.cpl is corrupted.
I just checked on an old ME install disk I have (it is inside \win9x\WIN_9.CAB\) the file there is 36864 bytes in size, dated 2000-06-08 and - once extracted - opens just fine in Dependency Walker. (this is an English version, I don't think I have handy an Italian version, that may well have different date/size, to check it)
In any case, if you open it in *any* hex/disk viewer/editor, its first two bytes should be (regardless of the version) the "normal" DOS signature of 4D5A or "MZ":
https://en.wikipedia.org/wiki/DOS_MZ_executable
jaclaz