Try unzipping the Android SDK and Resources with winzip or some kind of utility
Erel
"It is recommended to use a tool such as
7-Zip to unzip the large package. Windows Explorer might fail to extract it properly." should be
bolded, on the B4A install directions page, and
repeated under section 2 next to at least the larger download. I'd
word it more strongly, as in "Don't use Windows Explorer as it regularly fails to extract these large files properly".
Last night WIndows Explorer produced 2-3 different corruptions including causing the SDKManager to choke once (which led me to this old post).
No issues using 7-Zip afterwards.
I'd suggest also adding, "If you used Windows Explorer and encountered errors, delete c:\android and start over".