Compile Error in Hidden Module

Hi there,

I have been writing a tool for some other users and they encounter problems with one of its macros.
They receive an error message saying "Complier error in hidden module D_Input", while it runs stable for me.

- It's a macro to read a csv or txt file and put the data into the tool.
- It does not really feature any fancy functions or libraries, at least I did not manually add anything and all seems rather standard to me

I'm using Excel 2007 for designing and Excel 2000 for compatability testing, use Win 7 as OS. No issues here.
One of the users who gets the error is running the exactly same version of Excel 2007 (with same version of SP3), but on Win XP.
The other one is using Excel 2000, also on Win XP.

When googling the error, I mostly end up with some stuff on adobe and autostart settings that are messed up, but this does not seem to be the case here, since they can open and operate the tool alright, but just not this one macro/module. I'm only self taught and did never encounter sth like that before - can anyone give me a hint on where to start looking for a solution?

Are there any usual suspects I could check for?

When I check for links (not sure if thats the English term, German version says "Verweise") for the module, I see these 7 checked:

Visual Basic for Applications
Microsoft Excel 12.0 Object Library
OLE Automation
Microsoft Office 12.0 Object Library
Microsoft Forms 2.0 Object Library
Microsoft Calendar Control 2007
ATLContactPicker 1.0 Type Library

Could any of these be an issue?
Or could the error be caused by having a variable given a name that's also used somewhere else (e.g. in an Addin which they have and I do not?)