--- loncom/homework/structuretags.pm	2015/09/14 13:45:19	1.539
+++ loncom/homework/structuretags.pm	2015/10/05 02:35:40	1.540
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA 
 # definition of tags that give a structure to a document
 #
-# $Id: structuretags.pm,v 1.539 2015/09/14 13:45:19 raeburn Exp $
+# $Id: structuretags.pm,v 1.540 2015/10/05 02:35:40 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -1510,6 +1510,7 @@ sub start_problem {
     my $status;
     my $accessmsg;
     my $resource_due;
+    my $ipused;
 
     my $name= &get_resource_name($parstack,$safeeval);
     my ($result,$form_tag_start,$slot_name,$slot,$probpartlist);
@@ -1522,7 +1523,7 @@ sub start_problem {
             &Apache::lonnet::set_first_access($interval[1],$timelimit);
         }
 
-        ($status,$accessmsg,$slot_name,$slot) =
+        ($status,$accessmsg,$slot_name,$slot,$ipused) =
             &Apache::lonhomework::check_slot_access('0','problem');
         push (@Apache::inputtags::status,$status);
     }
@@ -1613,7 +1614,8 @@ sub start_problem {
             ( $status eq 'NOTRESERVABLE') ||
             ( $status eq 'RESERVABLE') ||
             ( $status eq 'RESERVABLE_LATER') ||
-	    ( $status eq 'INVALID_ACCESS')) {
+	    ( $status eq 'INVALID_ACCESS') ||
+            ( $status eq 'NEED_DIFFERENT_IP')) {
 	    my $bodytext=&Apache::lonxml::get_all_text("/problem",$parser,
 						       $style);
 	    if ( $target eq "web" ) {
@@ -1646,7 +1648,14 @@ sub start_problem {
                               &Apache::lonnavmaps::timeToHumanString($accessmsg,'start'));
                 } elsif ($status eq 'NOTRESERVABLE') {
                     $msg.=&mt('Not available to make a reservation.');  
-		}
+		} elsif ($status eq 'NEED_DIFFERENT_IP') {
+                    if ($ipused) {
+                        $msg.=&mt('You must use the same computer ([_1]) you used when you first accessed this resource using your time/place-based reservation.',"IP: $ipused");
+                    } else {
+                        $msg.=&mt('Each student must use a different computer to access this resource at this time and/or place.').'<br />'.
+                              &mt('Somebody else has already used this particular computer for that purpose.');
+                    }
+                }
 		$result.=$msg.'<br />';
 	    } elsif ($target eq 'tex') {
 		my $startminipage = ($env{'form.problem_split'}=~/yes/i)? ''
@@ -1666,8 +1675,11 @@ sub start_problem {
 		$result .= 
 		    &Apache::bridgetask::proctor_validation_screen($slot);
 	    } elsif ($target eq 'grade') {
-		&Apache::bridgetask::proctor_check_auth($slot_name,$slot,
-							'problem');
+		my $checkinresult = &Apache::bridgetask::proctor_check_auth($slot_name,$slot,
+							                    'problem');
+                if ($checkinresult = /^error:/) {
+                    $result .= 'error';
+                }
 	    }
 	} elsif ($target eq 'web') {
 	    if ($status eq 'CAN_ANSWER') {
@@ -1677,10 +1689,18 @@ sub start_problem {
                         $Apache::lonhomework::history{'resource.0.checkedin'};
                     if ($checked_in eq '') {
                         # unproctored slot access, self checkin
-                        &Apache::bridgetask::check_in('problem',undef,undef,
-                                                      $slot_name);
-                        $checked_in =
-                            $Apache::lonhomework::results{"resource.0.checkedin"};
+                        my $needsiptied;
+                        if (ref($slot)) {
+                            $needsiptied = $slot->{'iptied'};
+                        }
+                        my $check = &Apache::bridgetask::check_in('problem',undef,undef,
+                                                                  $slot_name,$needsiptied);
+                        if ($check =~ /^error: /) {
+                            &Apache::lonnet::logthis("Error during self-checkin of problem (symb: $env{'request.symb'}) using slot: $slot_name");
+                        } else {
+                            $checked_in =
+                                $Apache::lonhomework::results{"resource.0.checkedin"};
+                        }
                     }
                     if ((ref($slot) eq 'HASH') && ($checked_in ne '')) {
                         if ($slot->{'starttime'} < time()) {