Jomar,
I don't recall running into that error when generating an HMS project using GeoHMS. However, I have not repeatedly used GeoHMS to generate a lot of projects. I'd say I've used it less than a dozen times. Also, it has been a long time since I have used GeoHMS.
The error "System.Runtime.IteropServices.COMException (0x80004005): Error HRESULT E_FAIL has been returned from a call to a COM component." is a very generic error message. The HRESULT is a "tag" for a type of error code to distinguish certain error codes from other error codes. (HRESULT - Wikipedia ).
I am not a systems administrator. I don't have training on database structure. I'm no expert on discerning network or database errors, let along Arc Map errors. Having said that, I have gotten around this mysterious type of error by
- simplifying the names of layers, and
- running the Arc Hydro project on my local drive and on a network server.
When I started making my project names without spaces and as short as possible, frustrating and mysterious errors all basically vanished. When I started putting my .mxd (and therefore my Arc Hydro project directories on my local PC (C: drive)), the processing speed increased dramatically. If I do run into the errors, I will save everything, close ArcMap, and restart my PC. For some reason the errors will go away when I do that. I've wondered if the "undo" list gets too long and causes things to freeze up. Just my own "superstition".
So, if you haven't yet, you should put the .mxd and GeoHMS project on your local PC and make sure the file path names are short and have not spaces.
I also used Model Builder to "program" the steps needed to process the data. This helps me if I have to restart the process over and over to get past errors. it also documents the process. Most, if not all, Arc Hydro and GeoHMS commands can be run using the Toolbox tools and these can be "programed" in Model Builder.
Hope this helps.
Mark