Problem with downloading files from cache. Wingate 5.2.3

[AlexVPS]

Sometimes during downloading files connection with the Internet (for example about 25 % of downloading) is broken off. The file is located in a cache with the size of 25 % from the actual size. At continuation of downloading of 25 % of a file are loaded from a cache. Then there is a mistake and operation goes in cycles.
For an example: Having dug connections has taken place after downloading of 62437 bytes. The actual size of 279515 bytes.

Logfile:
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Connecting proxy 192.168.20.1 [IP=192.168.20.1:3128]
Connected.
GET http://www.epox.nl/BIOS/KRA23A28.zip HTTP/1.1
Host: www.epox.nl
Accept: */*
Referer: http://www.epox.nl/BIOS
User-Agent: Mozilla/4.0 (compatible; MSIE 5.00; Windows 98)
Range: bytes=60389-
Connection: close
HTTP/1.0 200 Document Follows
Date: Tue, 11 May 2004 08:48:46 GMT
Server: WinGate Engine
Content-Type: application/zip
Last-Modified: Fri, 05 Dec 2003 14:01:45 GMT
Content-Length: 279515
Error occured!
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After deleting a file from a cache manually the problem disappears. What it is possible to think up?