Apparently, you are the only person with such an issue.
If you got the same error (which relates to a missing function (LLMD5::hex_digest, and for the version shipped with v1.26.0.12, it should be "hex_digest@LLMD5@@QBEXPAD@Z") in llcommon.dll, something that normally cannot happen since the viewer won't start at all in such a case: this function is used in the login panel of the viewer, so you won't even be able to login), then it is obviously an issue with your computer.
Check for a spurious llcommon.dll copy, somewhere else than in the Cool VL Viewer installation directory but in a publicly accessible system folder (was there one such copy installed by another viewer in WINDOWS or WNDOWS\SYSTEM32 directories, for example ?... Or did another viewer add the path to its own directory (itself holding a llcommon.dll library) to the system PATH variable ?).
Or perhaps the viewer is trying to launch a plugin installed by another viewer and compiled for another llcommon.dll library... Check for plugins installed in system folders/PATH.
Another problem could be a still undetected virus on your system... which would explain the performance issues you got and the unrelated color scheme messages...
In any case, I cannot do more than trying to guess, given you don't even provide a log file (see the
rules for this forum, please).