It would only happen with TCMD and IDE; TCC doesn't use scilexer.dll.
The strange thing is that the message is coming from the Windows loader, not TCMD, and it should cause TCMD to fail to load at all (scilexer.dll is a required dll). Scintilla is used for the command input window in TCMD -- can you access that window? Can you access the IDE (ide.exe or BDEBUGGER) at all? Is scilexer.dll in your installation directory?