Toshiba Laptop; Vista 32 bit; OL 2007; MS Security Essentials; 1.5 Gb PST file; Ten days ago outgoing email returns error in title. Periodically, it will work. Went into MS Sec Essentials and exempted the documents folder and it works for 5 or so emails then reverted to error again. Have tried the following: sending messages through two ISP accounts RCN. com and Gmail. com with same result; compacted PST; run scanpst; removed MS Sec Essentials; exempted documents from Windows Defender after removing Security Essentials; removed most Add-Ons; and changed many other settings. If I go to documents, right click and click send email the attachment does attach and will go. I also use syncing net to keep two other desktops synced with this laptop. Am considering upgrading to Win 7 but afraid to until issue is resolved. Would remove OL 2007 and reinstall but it doesn't seem to be its problem.