Assuming that you did not do any adjustment with the antenna orientation or computer orientation, etc. I think the cause maybe a power/signal issue.
First have you checked whether or not you have set a country code in the .dat file? most chipsets have a setting which allows one to set to a country code suitable to where they live primarily because of radio communication restrictions.
Second is that have you tried to use other antennas, maybe more powerful ones or even directional ones?
Last but not least. I hear version 3.x from ASPj is from a new branch off serial monkey.. you may want to try the last of the 2.x versions.