It doesn't sound like you know what your talking about, lol.
There are several factors here, if your C: drive is full then you won't be able to download large files, and to check if this is the case right click on the C: drive and select properties, and it should tell you how much free space is left. If you are having trouble with the internet then it may be a network issue on your end, your modem may need to be reset, or it could be a problem with the ISP or the server/site you are connecting to.