Sebastian,
Your problem interested me.
I download and installed Capture Text from capturetext.com.
You should have a blue icon in the right-hand side of the main screen taskbar (the "notification area")
Right-click on that icon, choose Settings, is the box about launching at startup time unchecked?
If not,then uncheck.
Here is a capture of that settings screen made using the Win 7 Snipping tool.