What sort of network & hardware are you running? If it's a typical home wireless router using the 2.4GHz frequency band, it's possible you are running into interference affecting the access point (wireless router). Other networks/microwave radiation/cordless phones using the same frequency can affect wireless performance. Who knows what sort of crap the credit union is using that could affect your network if it's close enough.
1 - I live next door to a large Credit Union and it seems like during the week my wife and I get knocked off of our wireless more than we do on the weekends when the Credit Union is closed... I am pretty sure I am secured but would like to see if anyone is or has been accessing our wireless... how can I do that?