>as Lazarus itself informs me when I try to RUN after compilation
That is you only have the msg from lazarus, or you also checked yourself on the disk, looking for the exe? (sorry to be pedantic)
Maybe lazarus (run/run param) has a different exe name configured, or maybe the exe was created in an "output" folder, and lazarus did not expect this?
"unit not found" => is that while debugging, or if an error during compilation appears?
- A unit with code you wrote in the main project dir
- A unit with code you wrote in another dir
- a unit from a packacke or LCL (anything inside the lazarus folder, except the fpc folder)
- a unit of the rtl (anything in the fpc folder)