Being new to map making, I have only one real bug, but it is a big one.
The black circle shows this problem clearly. I have attempted to close down TE and reopen. Deleted TE, reinstalled, nothing works.

any help would be appreciated.
OS: Vista Ultimate Upgrade
Ram: 4 Gigs
CPU: AMD Phenom 9600 Quad-Core Processor ~2.3GHz
Video: ATI Radeon HD 4890