I've created a lead conversion trigger that is working in my dev org by not my production sandbox. I keep getting this error, which is strange because as system admin I clearly have "Edit" permission on accounts. Any thoughts?

Error Message:

Error: Invalid Data.
Review all error messages below to correct your data.
Apex trigger ConvertLeadtrigger caused an unexpected exception, contact your administrator: ConvertLeadtrigger: execution of AfterInsert caused by: System.DmlException: ConvertLead failed. First exception on row 0; first error: INSUFFICIENT_ACCESS_ON_CROSS_REFERENCE_ENTITY, You do not have the required permission. To continue, you must have the 'Edit' permission on accounts : : []: Trigger.ConvertLeadtrigger: line 13, column 1

The Code:

trigger ConvertLeadtrigger on Lead (after insert) {
//Bulkified
   Integer Count =0;
    Database.LeadConvert lc = new Database.LeadConvert();
    for(Lead Lea : trigger.new){
        if(Lea.Convert__c == 'Trigger'){
          Database.LeadConvert convLead = new database.LeadConvert();
          lc.setLeadId(Lea.Id);
          LeadStatus convertStatus = [SELECT Id, MasterLabel FROM LeadStatus WHERE IsConverted=true LIMIT 1];
          lc.setConvertedStatus(convertStatus.MasterLabel);         
          lc.setAccountID('001i000000gKtwA');
          lc.setDoNotCreateOpportunity(true);
          Database.LeadConvertResult lcr = Database.convertLead(lc);
          System.assert(lcr.isSuccess());  }      
    }
}