Downloads

Hello-
Hopefully someone can help me out there. All of the sudden both my desktop and laptop will not complete downloading any files. They usually start the download, but it then just stops. Although it looks as if it is downloading, it just stays at the same % download or # of kb’s. It doesn’t seem to matter the size and I have let a couple go for about 20 minutes and they were small. I have run Norton’s and cannot download the plug-in to run TrendMicro. I am currently trying Norton’s in safe mode. Help.
Thank you.