Your error may be related to the ADE feature which by default scans and creates a 2D footprint thumbnail for Generic Buildings that has been a part of ADE since version 1.7x was released.
Although IIRC ADE typically includes all files it needs to run its core feature set, the footprint thumbnail creation feature (provided as an external plugin by Arno), may have a dependency on a DOT NET 2.0 run time version and/or MSXML may not yet be installed in your version of Windows.
Also, if you have not yet separately downloaded and installed the footprint thumbnail package from the Scruffyduck download website, you should do so now, as it is not included with the ADE install package, and it will speed up loading most stock- and some addon- airports.
Note as well that you need to install the FS SDK versions and FSUIPC versions for any/all versions of FS that you plan to output airport BGLs for.
I hope I have not overlooked anything else, and that this info might get you up and running.
Otherwise, you might see additional recommendations here by other frequent ADE users before Scruffyduck replies, as AFAIK he is traveling at this time. ;-)