I also had this issue few day ago when downloading SVN (Windows 7 32-bit, TortoiseSVN). Tried searching with google for solutions, and some suggested even setting MTU to 1300, down from 1500 default.
- While MTU was set to 1300 i never had this error, but i didn't test it so long that this would be undeniable fact. It may have negative impact to other internet traffic on computer.
- After the error, SVN Update command always resumed downloading with no issues.