Odd server behavior

Unable to identify reason for odd server behavior.

My family type server provides file storage to family members across WAN. When downloading off some webpage (right click . save as,
in HTTP mode) the following occurs:
-if the file size is under about 10MB -12MB, then the save window pops up in 5 sec or less and download completes as expected;
-if the file is larger, then it seems to just wait there 'forever'.

Any Ideas?

SERVER:
AMD Duron 1.3Ghz
256MB PC133 SD-ram
Windows ME
Server software "Savant"
Note - this PC is just serving HTTP on port 80 and TCP on port 21, nothing else.

Curious