Hi ferallynx!
Can you give me more details? When happened this? This sounds like some problem loading the graphics.
The Tophet.exe must be in the same folder where the Data folder is so the graphics load correctly.
Are you using the 1.5 version? (I´ve seen some people still downloading the 1.2 build and this has even more bugs)
If the problem isn´t any of these look inside the Data folder, there´s two files named data and ndata. Send me these two files to Azardev@protonmail.com and I'll take a look at them.