I am having this same issue. I've increased the memory_limit and max_execution_time and no change. It seems to fail once the Memory usage gets to around 3,000kb. memory limit is set to 64mb. I thought the issue may be the site file path as the hint shows up as C:\Inetpub\...\...\httpdocs\generator/ whereas the document root i believe is just /httpsdocs/sitemap.xml
i've tried multiple variants of the file path and no change in behavior
Links depth: 2
Current page: viewitem.asp?idCategory=52&idProduct=359&priceRange=0x999999
Pages added to sitemap: 443
Pages scanned: 500 (9,114.5 KB)
Pages left: 168 (+ 2274 queued for the next depth level)
Time passed: 0:01:34
Time left: 0:00:31
Memory usage: 3,004.4 Kb