Saab - all agreed, but I think perhaps a significant number of computer users might not know they had been infected by, for example, 'perrun', and then this could happen
For the variant that appends to TXT files
Textrk.exe is then configured to open all TXT files by changing the (Default) value of the registry key
HKEY_LOCAL_MACHINE\Software\Classes\txtfile\shell\open\comma nd
to
textrk.exe %1
As Richard says - take care!