I'm making a call to an external RESTful web service from Apex code via Http, HttpRequest, and HttpResponse classes.

Here is my response:

{"response":{"error_id":"SYSTEM","error":"SFDC_STACK_DEPTH is not a valid HTTP header name","error_description":null,"error_code":null,"service":"auth","method":"POST","dbg_info":{"instance":"11.hbapi.sand-08.nym1","slave_hit":false,"db":"master","awesomesauce_cache_used":false,"warnings":[],"time":18.586874008179,"start_microtime":1359518018.7667,"version":"1.13.12.3"}}}

It's obvious that it's not liking the request header:

SFDC_STACK_DEPTH: 1

Any way I can not include this in the request?  Can I change the HTTP version (1.1 instead?)

Thanks,

Nathan