Problem adding opportunity to contact

[GoogleCodeExporter]

What steps will reproduce the problem?
1. Navigate to contact record (example: Marisa Levine)
2. Click "New Contact Donation"
3. Select any opportunity record type

What is the expected output? What do you see instead?
Expected: redirect to opportunity object
Result: Error message: The value of the "conid" parameter contains a character 
that is not allowed or the value exceeds the maximum allowed length. Remove the 
character from the parameter value or reduce the value length and resubmit. If 
the error still persists, report it to our Customer Support team. Provide the 
URL of the page you were requesting as well as any other related information. 

https://na13.salesforce.com/006/e?lookupcmpgn=1&retURL=%2FYAY+SPARK&accid=001a00
0001N0TkY&conid=YAY+SPARK&RecordType=012300000016WUQ&ent=Opportunity&opp3=Marisa
+Levine-+Donation+7%2F8%2F2013

What version of the packages are you using?
2.14

Please provide any additional information below.
This is only an issue on one record, as far as has been observed. Other 
contacts and opportunities working as normal. 

Original issue reported on code.google.com by tmy...@sparkprogram.org on 8 Jul 2013 at 5:21

[GoogleCodeExporter]

The Conid parameter here is incorrect, I'm not sure as to why it would be the 
case for just one account though.  When you say version 2.14, can you tell me 
what package that refers to?

Original comment by kbro...@gmail.com on 10 Jul 2013 at 2:46