diff --git a/pandora_agents/pc/ChangeLog b/pandora_agents/pc/ChangeLog
index edc0f2a263..e87f2ed8f8 100644
--- a/pandora_agents/pc/ChangeLog
+++ b/pandora_agents/pc/ChangeLog
@@ -1,3 +1,8 @@
+2012-05-30  Ramon Novoa  <rnovoa@artica.es>
+
+	* pandora_agent: Merged from unix agent. Check for valid regular
+	  expressions before adding module conditions.
+
 2012-04-25  Miguel de Dios  <miguel.dedios@artica.es>
 	
 	* DEBIAN/postinst, DEBIAN/make_deb_package.sh: disabled the checking
diff --git a/pandora_agents/pc/pandora_agent b/pandora_agents/pc/pandora_agent
index 82706381bd..080af0b8fa 100644
--- a/pandora_agents/pc/pandora_agent
+++ b/pandora_agents/pc/pandora_agent
@@ -220,7 +220,8 @@ my $OS_VERSION = guess_os_version ($OS);
 # Windows specific modules
 my $Win32 = undef;
 if ($OS eq 'windows') {
-	use PandoraWin32;
+	require PandoraWin32;
+	PandoraWin32->import();
 }
 
 ################################################################################
@@ -241,6 +242,22 @@ sub error ($) {
 	`logger -i -t pandora_agent_daemon [ERROR] $msg 2>/dev/null`;
 }
 
+################################################################################
+# Check a regular expression. Returns 1 if its valid, 0 otherwise.
+################################################################################
+sub valid_regexp ($) {
+	my $regexp = shift;
+	
+	eval {
+		'' =~ /$regexp/;
+	};
+
+	# Something went wrong
+	return 0 if ($@);
+	
+	return 1;
+}
+
 ################################################################################
 # Recursively delete files and directories.
 ################################################################################
@@ -405,7 +422,11 @@ sub parse_conf_modules($) {
 				push (@{$module->{'precondition'}}, {'operator' => '()', 'value_1' => $1, 'value_2' => $2, 'command' => $3});
 			# Regular expression
 			} elsif ($action =~ /^\s*=~\s+(\S*)\s+(.*)$/) {
-				push (@{$module->{'precondition'}}, {'operator' => '=~', 'value_1' => $1, 'command' => $2});
+				if (valid_regexp ($1)) {
+					push (@{$module->{'precondition'}}, {'operator' => '=~', 'value_1' => $1, 'command' => $2});
+				} else {
+					log_message ('setup', "Invalid regular expression in module precondition: $line");
+				}
 			}
 		} elsif ($line =~ /^\s*module_exec\s+(.+)$/) {
 			$module->{'func'} = \&module_exec;
@@ -462,7 +483,11 @@ sub parse_conf_modules($) {
 				push (@{$module->{'conditions'}}, {'operator' => '()', 'value_1' => $1, 'value_2' => $2, 'command' => $3});
 			# Regular expression
 			} elsif ($action =~ /^\s*=~\s+(\S*)\s+(.*)$/) {
-				push (@{$module->{'conditions'}}, {'operator' => '=~', 'value_1' => $1, 'command' => $2});
+				if (valid_regexp ($1)) {
+					push (@{$module->{'conditions'}}, {'operator' => '=~', 'value_1' => $1, 'command' => $2});
+				} else {
+					log_message ('setup', "Invalid regular expression in module condition: $line");
+				}
 			}
 		} elsif ($line =~ /^\s*module_intensive_condition\s+(.*)$/) {
 			my $action = $1;
@@ -477,7 +502,11 @@ sub parse_conf_modules($) {
 				push (@{$module->{'intensive_conditions'}}, {'operator' => '()', 'value_1' => $1, 'value_2' => $2});
 			# Regular expression
 			} elsif ($action =~ /^\s*=~\s+(\S*)\s*$/) {
-				push (@{$module->{'intensive_conditions'}}, {'operator' => '=~', 'value_1' => $1});
+				if (valid_regexp ($1)) {
+					push (@{$module->{'intensive_conditions'}}, {'operator' => '=~', 'value_1' => $1});
+				} else {
+					log_message ('setup', "Invalid regular expression in intensive condition: $line");
+				}
 			}
 		} elsif ($line =~ /^\s*module_crontab\s+(((\*|(\d+(-\d+){0,1}))\s*){5}).*$/) {
 			$module->{'cron'} = $1;