_com_util::ConvertStringToBSTR - Access Violation

_com_util::ConvertStringToBSTR - Access Violation

I'm invoke COM server's method and randomly get access violation error in
the _com_util::ConvertStringToBSTR:
g_quote->RegisterQuote(_bstr_t(pszTicker), _bstr_t(_T("*")));
More information:
int GetQuotesEx(LPCTSTR pszTicker, int nPeriodicity, int nLastValid, int
nSize, struct Quotation* pQuotes, GQEContext* pContext) {
const RecentInfoMap::const_iterator it = g_mapRecentInfo.find(pszTicker);
if (it == g_mapRecentInfo.end()) {
g_quote->RegisterQuote(_bstr_t(pszTicker), _bstr_t("*"));
return nLastValid + 1;
}
}
I don't know why this bug happens. I can provide additional info if needed.